“The Rules” is a Moneyish series where we define the rules around sticky money or workplace topics.

It’s never too late to fix your tardiness problem.

Fifteen to 20% of the U.S. population say they’re “consistently late,” particularly for work, according to one 2006 survey. Almost one in five workers says they’re late to work at least once a week, a 2014 YouGov poll found, with 22% of millennials admitting they fall into that category. And lateness can impact the bottom line — costing American businesses upwards of $3 billion in lost productivity every year, by one estimate.

“I think it’s partially because many of us (are) living in the world of rose-colored optimism, where we’re constantly thinking best-case scenarios because we’re all jamming so much into our days,” etiquette expert Thomas P. Farley told Moneyish. “Technology enables us to stay in touch with more people, to take more appointments … so we’re just cramming more in.” (Research has indeed linked multitasking with lateness.)

But habitual lateness — whether it’s in a workplace setting or a social one — signals that you’re disorganized, disrespectful and selfish, Farley said. Here are the rules around tardiness for work, social outings and family gatherings, according to experts, plus tips on how to never be late again:

Also read: The smartest way to let your boss know you’re running late to work

For work in particular, Farley said, “even one or two minutes late is not on time — you are late.” For commitments like conference calls or meetings, he added, “you really should be striving not just to be arriving on the stroke of the hour when the meeting is commencing, but rather, you should be there early.” Don’t wait until seconds before your call begins to realize you don’t have the dial-in code.

“I wouldn’t suggest for anyone to arrive late for work, unless something transpired that prevented them from being there on time,” etiquette expert Elaine Swann said. But, she added, “I think the level of tolerance is subjective depending on your coworkers, your boss, your supervisor, your company policy and the culture at your job.”

If you’re late to a meeting, don’t rush into the room “in a big kerfuffle of excitement and energy,” Swann said. Instead, locate a seat before walking in, beeline over to that seat and sit quietly until it’s your turn to speak. Apologize for your tardiness without going into detail — you can always explain your reason to the relevant person later — and move on. “You don’t want your lateness to be a serious distraction to everyone who’s there,” Swann said. “You want to walk in, sit yourself down and be quiet.”

If you’re meeting friends for a predetermined reservation, show up early, Farley said. Keep in mind that many restaurants won’t seat a party until every member is present.

Don’t make lateness your M.O., even with friends. “I think every now and then, five minutes (late) is fine,” Farley said. “But I would still not want to make that your regular habit. If you’re consistently the last one out of your group to be arriving at a common meeting place, you’re going to get a reputation of a person who’s not organized enough to show up on time.” If someone’s tardiness becomes a pattern, he added, “we start to feel like we’re being taken advantage of — and frankly, whether that’s the intention or not, that’s the net result.”

Also read: These are 8 of the weirdest excuses workers made for being late last year

Don’t be that person who’s always blaming transit issues. “Sure, we’ve all been there. And yes, there are those once-a-year situations where you’re on a subway that just shuts down for an hour with you trapped inside,” Farley said. “But to be consistently blaming traffic, to be consistently blaming the transit system, I think that’s a cop-out.” After all, he pointed out, travel delays are usually a known quantity — and while planning based on the ideal travel conditions may work on your lucky day, “not every day is going to be your lucky day.”

“If you’re factoring how much time it’s going to take you to get somewhere,” Farley added, “don’t ever, as your baseline, use the quickest time you ever got somewhere.” Think of how long it takes you to get from point A to point B 85% of the time, he suggested, then build in a 10% margin of error. Swann urged mentally working backwards from the time you need to leave, rather than the time you need to get there. “Your deadline should be the go-time from home,” she said.

Give an early heads up once you know you’re running late, so the other person can adjust their departure time accordingly. Don’t text your friend that you’re running 20 minutes behind a minute before you’re supposed to meet, Farley said. “I could’ve been doing other things myself, and maybe in fact I would’ve welcomed the extra time to get ready.” The more notice you can provide, the better.

For dinner at a family member or friend’s house, Farley said, it’s OK to arrive fashionably late by 15 minutes or so — but overall punctuality is still important, given the science of timing that goes into serving meal courses. For an open house or barbecue-style gathering to which guests will arrive in waves throughout the day, he added, it’s fine to arrive a few hours after the event begins — just call the host ahead of time to make sure.

Be early, not on time. Farley harks back to football coach Vince Lombardi, who famously functioned 15 minutes ahead of schedule. And as a selfish perk, Farley said, you’ll have a greater degree of control over factors like how you present yourself and where you and the group are seated. “You could have the address wrong; your phone could die; your Uber driver could get lost,” he added. “Rather than dealing with the anxiety of all these things, give yourself the gift of factoring in extra time. And then bring a book; catch on email once you’re there.”