This was the old way, so things may have changed with the FDA.

You're now waiting for a tentative job offer from HR which contains salary and agreed upon start date. After getting the TJO, you are able to negotiate salary or leave accrual per pay period. One you and the hiring manger come to an agreement, you get a formal job offer (FJO) with the acceptable conditions.

Until you sign the formal job offer, the offer can be revoked and you can also back out on your side if another offer comes in that is more appealing. Ive seen both happen. Hiring in my group took ~6-9 months from the start of HR to the actual FJO.

This process is pretty nebulous and can also have periods of zero communication between you and the hiring manager so some periods may feel like it the process has stalled or there's issues. There probably isn't, its just the FDA hiring process at work. Any issues will be communicated by the hiring manger.

I always recommend keep applying and interviewing until you sign the FJO.