salaah time

Performing Esha Salaah once the time sets in

Q: My question is about differing start and finish times for Salaah. The mosques I have near to me have different times for Salaah. For example one mosque start time for esha is 9:30pm and another is 10:20pm. If I usually pray in one mosque can I follow the timing for the other, again as an example I follow the mosque with the 10:20pm start but offer my esha prayer before that as the other mosque clearly starts at 9:30pm. Is this permissible?

Combining Salaahs

Q: I am giving exams when I depart from my home. It's Zohar time so I offer it but when I arrive at my home, it's maghrib time so can I offer Asr Salaah at Zohar time or at Maghrib time?