Macbow, by glueing the power lam to the core prior to backing, you have the oportunity to sand the ends of the powerlam for a totally smooth transition onto the core, thus eliminating the problem of voids in your glue joint at the ends of the power lam when you glue backing to core. I'm seldom on a schedule to complete a bow as I build them mostly for my own amusement, so watching glue dry isn't a big deal for me. still, is just cause for having 3 or 4 bows in progress all the time, which I do. always something to do thataway. otherwise, it's a good excuse to turn the dog loose and get some fresh air.
E, with the vast knowledge and experience present here, I'm surprised nobody else suggested it. maybe it's a closely guarded bench secret. well, not now I guess.
:D