kegels! when to start?

Katie
I'm nearly 3 weeks pp.
I couldn't even do a kegel after giving birth, now I can do one but it's  def not as strong. Are you ladies doing them? When did you start? 
I also feel like I can't do a sit up yet... Muscles just totally gone! 
When should I start to try? It's annoying trying to get out of bed ...