Brief report:
Started out from our IMSS cabin at 4:07am. Got off route while in the forest and ended up climbing the left north chute of the thumb rock that you see from Puebla. This was where the 3 dogs that followed me stopped. After the thumb rock I had to downclimb towards the saddle on the north ridge. Finally, picked up the correct trail and got to the summit at 8:33am. Clear day, but windy. Left the summit at 9:07am and was back at our IMSS cabin at 10:50am.