Here, 'this April' is fine. 'Last April' to me means 'April last year' if I'm talking in May but if I'm talking in December, what would people understand by 'last April'?
I hope it's OK to bring in my thread and kind of merge the two around the next/last question. I use days, but the principle is the same: if I'm talking on Sunday, what would people understand by 'next Thursday' and would they understand the same on Monday?
Interested in Language