How long is 90 days?
At first glace, that may seem like one of those trick questions like "Who's buried in Grant's Tomb?" But 90 days doesn't always take three months, particularly if you're talking about the 90 days it takes FDA to review your 510(k) application.
By law, FDA must respond to your 510(k) within 90 days, and typically they do. The thing you have to understand is that FDA measures 90 days about the same way the NFL measures the 60 minutes in a football game. It's not unusual for the clock to spend more time stopped than running.
About 45 days after you submit a 510(k), you'll typically get a letter from FDA with questions. That serves about the same purpose as a quarterback throwing the ball out of bounds: it stops the clock. Your board of directors might be crossing days off the calendar, but FDA has already gone to commercial by sending a letter that you've been put on 30-day hold.
If your team is ready for this, they can spring into action and answer the questions necessary to get the clock running again. But don't be surprised if it takes more than one set of questions. And if you're not ready for one of the questions FDA has, the ball might get thrown out of bounds again.
So as you're making a project plan, be sure you don't expect to announce your clearance 90 days after the application is submitted. You may get clearance in 90 days, they just won't all be consecutive days.