Student or Learner
Put the customer on hold only if it is absolutely necessary. No one likes to be left on hold indefinitely. If you must put a customer on hold, estimate the time of the wait and ask whether he or she would mind holding. If you do have a caller on hold, check in with the caller every 45 to 60 seconds. A minute is a lifetime when you are on hold.
Does the time of the wait sound natural to you? Would "the wait time" be correct?
Would it be incorrect to say estimate the wait time instead?