I took my guitar in to have some buzzing sound fixed, and was told it would take about a week to fix.

I have been playing 7 weeks, is this going to seriously throw back my progression, or worse, cause me to lose my callouses?

= /
No, it'll be fine. Surprising the tech wants a week to do an hour's work, though.
I pick up my guitar and play
Just like Yesterday

T C Ellis Series 2 LP w/Skatterbrane Quiescence pups
Cort EVL-K6
Yamaha RGX211 modded
H&S Electric 12-string
Shaftsbury Ricki 4001
'84 Fender Yale
Roland Cube 15x

I went without mine for 6 days around the same time. (I'm coming up to three months now). By that time my fingers had toughened up a fair bit. My callouses might have softened up slightly but it was largely inconsequential I think. I missed the guitar but not problems when I picked her up again.
Tell the repair shop that you really, really need it back badly. Call twice a day. .
It's a squire strat. I brought it in and told the woman it was just having some buzz on the A string, and I read to just tighten/loosing the screws near the base to raise the action, but didn't want to because I might void the warranty in case something actually goes wrong. She said she would take care of it and they'd give me a call in about a week. = /
Lucky you, my Gibby will have been at the shop for 4 weeks tommorow because my dog chewed on the headstock and im having another pickup installed... So I went from Gibby back to Epi SG Special and it SUCKS!!! I would have just done the set-up myself if it was just raising the action a week is crazy...
1987 Ibanez Jem 777LNG #124
2012 Herc Fede PMC Jem
1987 Ibanez RG550 Road Flare Red-R
Marshall JCM-1 W/Lead 12 Cab.
Wampler, Ibanez, MXR, Morley Pedals