It depends what you mean by ‘last’.
If you actually mean ‘last’ ie after all the painting and final assembly etc, that’s not even possible!
We’re not talking about wheel alignment for chain adjustment. We’re talking about wheel and sprocket alignment at the build stage.
Depending how radical you’re being with choice of parts, width of tyres, etc will dictate the work that needs doing (moving or modifying the swinging arm, making dished gearbox sprockets, cutting the rear of the primary case away, moving the gearbox over, etc, are all things that are done).
It needs sorting now IMHO. FWIW, this is how I do it:
1) check the frame and yokes etc are true
2) set the front wheel dead centre in the forks
3) set the rear hub position by aligning the sprockets
4) with the rear hub and front wheel set, use laser or straight edge etc to calculate required rear rim to hub offset
5) fit and check and repeat step 4 as required
6) number of reputations of step 4 dictated by your accuracy of measuring !