Taking my son to nursery

I'm finding it so hard to leave my son at school he's 2years and a very loud and bubbly boy. Not shy of the line light at all, started school 2weeks ago and everything has gone wrong. He screams when I'm gone th second day of school he didn't stop for 2 hours I had to come and pick him up !! 

I now take him at 8am and leave him for 20-30mins and increase this everyday. But still no improvements going on to the third week now and I'm stick with what els I can do for him, as when Im there he has so much fun and interacts not bothered that I'm there but when he notices that I'm not he goes in to a panic switch!! 

Stuck x