MP2791 - Circuit to help turn on power to system

I just need help with a circuit that will help to give initial turn on to my system so it can boot up and then protect. Currently I have the MP2791 that will protect my battery but it needs to feed the 12V, 5V and 3.3V regulators (which power the rest of the systems electronics and the MCU that controls the whole board). My problem is that I need to power up the MCU so it can take control of the digital inputs to the MP2791 at initial start up. I would prefer it to be all controlled off of a simple switch.

Any thoughts are welcomed. Thank you.