I did a quick test with UniTolProd1.After I build cbases, I need up to ~t25-t35 to get rlabs as usual ... !The research labs are atleast 25 turns into the game vs. 15 for most production races.
With building 4 cbases first, it took me 38 turns to research rlabs and another 4 turns to build all of them. So t42 for UniTol if you build cbases first. If you just research rlabs first it's around 15 turns but then you wouldn't have very many places to build them.
You would probably add 10 turns to that for Feudalism so it's rlabs probably wouldn't be built until t52-60 with building cbases first.