when they're ready It can be hard to wait for them to start doing things, I guess. We're not good as a society at stoping and smelling the roses I think
All babies are different.My DD is almost four months and has been smiling for ages and if you tickle her and nuzzle her face she really giggles.She will also hold a small rattle but you have to put it in her hand.I know its hard but there are no real hard and fast rules and its so easy to fall into the trap of comparing your baby to others.Just enjoy her as she will grow up so fast.