I had the luxury of taking 2 days off around a weekend so did 4 days at home to potty train. Sent back into nursery on day 5 with loads of changes of clothes. Averaged 2 accidents a day at nursery for the first week but then got into the routine of it. Nurseries know the drill and will have regular toilet breaks which helps.
Maybe try Friday-Sunday at home potty training then pack loads of underwear and trousers in his bag for nursery. Bring a potty from home if he prefers it, or tell him about the toilet at nursery. Be prepared for accidents. They should help support him fully with it :)
We just wear pants at home but pull ups for nursery as he still wont potty thier so he uses tiolet at home fine we go shops and he ok we havent tryed days out yet but hoping he starts goin at nursery as my boy goes 5 days a week 12-3