13 months is very young imo, just watch the shooters arent trying to blow smoke up your arse for a free line.
My brothers lab is 20 month old, but was started when very young and has a full grouse and pheasant season under his belt already, as well as a lot of rabbit shooting. He will be getting put to a pointer bitch withing the next 6 months at which point he will be over 2 year old, just.
It depends on how much the dog has done, was he easily trained, has he got good breeding? At the end of the day he is your dog, but you must breed responsibly. Tell the shooters if they wait untill th