I am patiently awaiting my new PS-90 at the moment and have every intention to SBR it. I am also looking to build another AR15 for the purpose of SBR'ing it.

Question being, after you fill out the paperwork, submit it, and get your stamp back, are there any "reasonable timelines" which you have to get the weapon assembled?

As in, would the PS-90 SBR need to be done soon after I receive the stamp? Can you wait a week? A month? 6 months? A year?

Would the AR-15 need to be all complete except the barrel as soon as I receive the stamp?

The AR concerns me as well, I am getting the "election jitters" and would rather buy a lower & barrel and sit on it with the paperwork in hand so I can buy a few more "bannable" items.

Thanks for the time everyone, hope to be seeing a lot more of this subforum

There isn't a time requirement for the complete "build".  However, you should get the necessary engraving done in a timely manner.