Some plants are sporadic blooming and bloom as each new growth comes up and matures. Others are seasonal and bloom on all the growths generated during the year at one time. This depends on the plants parents. Be sure to ask about this factor when buying them. Repotting is only necessary when the body of the plant has grown over the pot or the media breaks down and won't allow the roots to dry between waterings.
Plants usually outgrows the pot before the media starts staying soggy.
It's best to repot when you see signs of new growth. Take the plant out of the pot. Gently remove as much of the old media as will come off the roots. Remove any bad roots. Put drainage material and media in a pot.