I also filed on March 12 and when I check on "Track my Refund", it still shows in process. Here is the exact wording..
.If you filed a complete and accurate tax return, your refund should be issued within 21 days of the received date. However, processing may take longer under certain circumstances.
So, I think you are still OK as far as the IRS timeline is concerned.
I will wait at least 3 weeks before I check again.
I actually already received my State refund.
