Hi and welcome to BB!
Just wondering if it might be helpful to introduce other sleep associations which may help the transition, such as a "lovey" or even just certain words like "time for sleep" or any other sleep cues which you can introduce now so that when he goes to daycare he will have other sleep associations instead of boobie to make it a bit easier? sorry i dont have experience with daycare but my DD is an avid feed to sleeper and i have always wondered how she would cope. I also agree with others that they often cope better than we think when we are not around. Best of luck and i hope the transition into daycare goes smoothly for you both