Just keep looking at them and see! if they dont bloom try more light. My drumbeat sits in almost full sun with some shade in the after noon. so far so great! its happy now so im happy. on my drumbeat the sheaths appear when the leaf growth seems to slow down a little then they start to peek out. but that's my plant so just keep looking at those new growths for anything different.
The flowers were amazing! and lasted quite long! a month for sure!