When are they supposed to crawl??????

So today as I was drying my hair, I kept checking Logan, as he was playing on the floor with his toys. At one check Logan was on all fours, and had himself rocking back and forth. He then proceeded to launch himself forward to get his soother.......just an hour later, he was on all fours and was then pulling himself forward with his arms. OMG!!!!!!! It's too soon.