There are 1245 total delegates at stake on Super Tuesday. It is looking very likely that with the 244 that he has now, Trump will likely be the official nominee when counting is complete on March 5th.
He will only need to pick up an addition 971 over the next three days. There are 19 delegates available on Sunday in the Washington DC primary. It is a closed primary, so Trump is likely to win most if not all, but because it is DC after all, we will have to wait and see what the actual outcome is.
I am coming up with about 870 total delegates at stake on Super Tuesday.
It will probably be March 19 when President Trump clinches the nomination.