Feeling like a bad mom

An

My son just started day care and I feel totally behind. The other kids seem to have to hang of it and are totally comfortable but my son will cry for 10/15 min when i leave. They tell me after that he warms up and has fun but idk why I waited so long to start. I feel bad bc the only interaction he had with other kids his age is when we go to the park - which Is nearly everyday but only for 30/45 min. He’s somewhat shy but doesn’t have a problem warming up to others.

I’m fortunate enough to not HAVE to send him to daycare bc my family watches him but for the sake of him interacting with other kids I want to try and take him 2 times a week for now... any suggestions on how to make him comfortable when I’m away?