Holi Celebration is start now. but if u want to enjoy this fully u can go after 12th of march. yes about all temples are open on 21st. Best place for holi celebration is Barsana and Nandgaon. after that the best placa for celebration is Raman Reti.. these 3 places holi is awesome. otherwise u can enjoy holi celebration in banke bihari , iskon , janmbhumi and any other temple too.