My experience with ATF-NFA (being a past ffl holder)(and owning numerous "NFA" items is that when your paperwork goes pending after the check/money order is cashed/deposited.
For the most part you got at least a 3-5month wait for SBR"S, SBS, AOW"S.
"Cans" & DD's on the other hand 4-7 months.
I just recieved a "DD"(form-1) that i did 6 mos ago, & a "can" paperwork (form-4) which was sent in 4 mos ago, but thats not to say the times can be longer or shorter.
For example i just transfered/purchased in (2) machinegun recievers to my "PD" and the paperwork was back in just under 14 days....so any one who tells you "because you have done this before, it will speed up your paperwork" is lying to ya!
Fact remains, theyll get it done when they feel like it, and im sure the "budget" thing whilst being a gov't employee wont spped anything up either...lol
Hope this helps-sorry if i ramble a bit....