Hi guys,
Yes, 'to get it' is an idiomatic way of saying 'to understand it'.
I can ask someone 'Do you get it?', or 'Did you get it?' or 'Have you got it?'. I can even use future, eg I don't think I'm going to get my teacher's explanation'. All tenses are possible in theory.
In practice, we usually use this of the past and present rather than the future, and often shorten it simply to 'Got it?' or 'Get it'? Here's a short conversation:
Boss: Get it?
Employee: Got it!
I'm not sure if I completely answered the original question. If not, please write again.
Clive