NOT A TEACHER.
I think you might find this post useful. Both are OK, but the first seems to be the better choice. Hope this helps!
Student or Learner
I will let you know once I hear/have heard from him.
Should "hear" or "have heard" be used in the above sentence? If "have heard" should be used, could you let me know the reasons?
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.