It all depends on you, your local conditions, the state of each hive being split, and what your technique will be.
Presently, I'm splitting my hives, vigorously. I prefer taking the original hive and moving it to a new location (a few yards away), then placing a new hive at the old location, with one or two combs from the original hive, containing emerging worker brood, and the old queen - filling the remaining space with empty comb, foundationless frames, or some of each. The old queen, with the majority of the field force and some brood and nurse bees, soon lays up much of the empty comb, creating a new brood nest. Then, in a few days I remove any queen cells produced by the new split and introduce a ripe cultured queen cell.