When to start/tips on transitioning

My little girl just turned 3 months and is still super dependent on me which is fine, I know she's a baby and needs her mama. But I mean she will not sleep during the day unless it's in my arms. I've been trying to get her out of that since she was 2 months old and it got to the point where she was getting sleep deprived and not sleeping during the night because of it. I kinda gave up and decided to keep trying here and there but I don't think I'll get strict about it until she's 4 months old as she should be able to self soothe by then. Is that a good time? I need all the tips i can get!