Assuming he has been exposed to gunfire as a good thing,he is not to young. Take it easy. short hunts and he is learning the field!keep it happy and fun.
Been a lot of years but recall one lil pup in particular went every where i did first hunt.
I started most pups about 20 minutes for their early hunts. Tried to get them out often but mindfull of soft joints first year. Have fun !
Rat terrier in pic?.