Arduino LMIC: cannot receive downlink messages

I was assuming that the reason why I am not receiving the download packets is that there is something wrong with the way my code is working.

Would I be wrong to assume, for now, that receive portion of the code is not waking up in time for the download message to be processed or is closing too quickly.

That said, I was wondering how I could track the start and end times when each window opened once the TxDone function was completed.