Making an early start for drone mother colonies

[meadowbank]

Here in NW England we have late and wet springs so I have decided to go for instrumental insemination. I would like advice on how to get the earliest drones before starting queen rearing when they are at the purple eye stage.
Protein requirements are obviously high.
Is it best to combine several overwintered colonies to give a chosen queen a vastly increased load of stores and emerging brood then cage her on a drawn drone comb.
I have some 35 colonies overwintering.
What is the time scale of stimulating the first drone eggs?
For example is incoming real pollen necessary or will stored pollen frames and supplement patties be sufficient?