I ordered a Bumbo yesterday (with a play tray). Lily has really good head control, but it'll probably take a while until she gets used to the Bumbo, because at first she really hated her rocker chair, but now she loves it.
When she's in it I'll probably just put a few rattles on the play tray for her to look at and attempt to grab. But she usually just likes to look around and look at the window and TV, so she doesn't really need a lot of entertaining.