Most clinics will want you to wait at least six months after delivery of your baby before undertaking pre testing for IVF. Pre testing involves some blood tests, an ultrasound and at some clinics a sonohysterogram. If you intend to breastfeed your baby you will also have to wait a few natural cycles after ceasing breastfeeding to allow your hormones to return to normal.
In the meantime you have lots of time to research clinics and prepare for consultations. I saw your post over on the member HT board. As you are so young, I think you have an excellent chance of success at the right clinic.