1994 Chevy Truck firering order and timing

Well I took my truck to a shop to set my timing and they put a timing light on it but never put the number one piston at top dead center. Should they put the piston at top dead center before they put a timing light on it. When I drive it it seems to me it is missing real bad but when I get up to about 60 or 70 it drives alright but it still misses a little bit