It depends. Last night I ran 8 or 9 NICS E-checks and all but one were "proceed" immediately (within a second of submitting). The one delay researched for 10 minutes and then was delayed.
There seemed to be a spike last weekend, when it seemed every NICS check we submitted was delayed. And we were on hold for an hour and a half waiting to submit a couple of checks over the phone, when the e-check system was not letting us login.
Could another spike happen this weekend and it happen again, sure, but you never know. All you can do is try.
Not an FFL but my total time in store was 10, maybe 15 minutes on Wednesday. Probably not really much pressure on NICS right now because most of the firearms are sold out...