Got a bike stand? and is the seatpost installed yet?

If so...

Then do the bottom bracket, crankset, pedals.
Then the headset, fork, stem, handlebars
Then the brakes, FD, RD.
Then the any bosses, shifters, brake levers.
Then the wheels with tires/tubes mounted (rear with cluster installed)
Then housing and cables - adjust brakes and derailleurs.
Lastly finish with saddle and grips or handlebar tape and accessories
(e.g. bike computer, rack, lights, reflectors, etc)

Notes: All things that could become cosmetically soiled, like saddle and handlebar grips/tape, I do toward the end for that reason - don't want them dirty. The other consideration is leverage and testing while assembling the bike. You really can do a final adjust on threaded headset/fork until you have it on the ground, with front brake attached and can rock the bike back and forth. The hand on the fork wobbling it in the stand doesn't reflect the reality of actually riding and braking as it stresses the headset. So the above list isn't set in stone. And I put on pedals early, because once the wheels and derailleurs go on, you betcha you'll want to turn the cranks. Hence your hand will want the pedals there. Again, it gives better leverage to rock the crank side to side as well to test for BB play. But YMMV.