It depends on the hamster
When we first had Charlie (we got him in the Summer months) he was out and about in the evenings. But once it got to winter he wouldn't come out much before 11pm and mostly that is his habit although sometimes a bit earlier.
I did what our RSPCA book suggested - which was to wake them at about the same time each evening (say 6pm or 7pm) if the pet belongs to a child, so they can interact. You wake them by being a bit noisy while putting the food out, a bit of noise cage door opening for example. This gradually wakes them and they will either come out to investigate or you can tempt them out with a treat in the end of a tube (that's what we used to do!)
The RSPCA book says it's fine to do that but best if it's done around the same time each night. So we wake our hamster for his out of cage time early evening.