fluffy, dd was 11 months when she started nursery. She was still breastfed, rejected bottles, hardly ate solids, had separation anxiety, would only fall asleep with nursing or in moving buggy, co-slept in my bed.
We settled her in very gently. Grandma did the drop-off. Perhaps about 5 mins chatting with carers, then say goodbyes casually, like nothing is wrong, hand to carer to cuddle, then LEAVE. The howling, if any, should stop after a few minutes. The carers will call you anyway, if it goes on for too long. When I pick up, I always peep through the door (out of dd's sight) to make sure she was not crying.
If you are worried about cuddling to sleep, make sure the carers are prepared to do that for your ds.
Dd gradually increased her sessions from a few hours to a few mornings and finally fulltime at 16.5 months. Now at 3.3, she rules the nursery.
You would be amazed. Dd was the last baby I expected to settle at nursery. But she is a different child almost. Less clingy and more adventurous. I think children get very different things from a nursery, like socialisation, activites, which at 10 months, your ds is able to appreciate. hth