I always put a little air in the tube before I finally fit the second bead. It stops the tube from folding and getting pinched.
I add and take out air 3-4 times during the process to INSURE the tube is straight, and I've always changed my own tires. once water gets in thru the spoke nipples, the talc turns to smudge, so the purpose of talc is in the initial centering/seating slippage only.
that redundant in and out of air to center makes talc unneeded.
what if you believe in talc religiously, and do a tire on the side of the road without talc availability...can you still believe in the fix?
to talc or not to talc...that is the question.
go for it if it's handy, but don't lose sleep over it if it's not.