So many changes at once...

So, Tucker is about 3 1/2 months old now and we have still not stopped swaddling him! Partly because he sleeps really well and why fix it if it ain't broke, right? But, also because it's scary to change something that's been our routine for this long! Lying in a sleep positioner is also part of our routine! So, now that he's rolling over some and controlling his head/neck a little better, I figure it's time to start letting him sleep on his belly. We decided to try it for the first time this morning, during his best nap of the day, to see how it works. So far, so good... but it's a lot to change at one time--no swaddle, from back to belly, and no sleep positioner (although we did still use the positioner this morning)! Any suggestions on dropping the swaddle or going from back to belly during sleep? Thanks!