The NYT reports 33.8M one dose recipients and 10.5M two dose recipients so far in the USA. [total 54.8M doses]
Current injection rate is 1.56M per day (also per NYT)
April 1 is in 48 days.
April 15 is in 63 days. (cite: calendar)
63*1.58M = 99.54M shots by April 15
My rough estimate is 54M fully vaccinated and 42M single shot by 15 April. Sounds good to me, but I don’t know how big groups 1 and 2 are. And the J&J rollout should improve these numbers.