I think you can train them at any age, I read on here about a dog who didnt get his SchH1 until he was almost 10. Not sure what makes a good IPO dog. Does he have a lot of SchH/IPO titled dogs in his pedigree? Some things I noticed about Berlin..is his prey drive, eagerness to learn, when I take him outside, he 'tracks' with his nose down the whole time (bear with me here, im a newbie too, but I believe I read in IPO they want the dog to track with their noses down and NOT sniff the air), and his intensity with 'tug'. Read up on it, as I have done hours of research on IPO and the BH and im *still* very lost. hahah. Also, go check out a club and talk with the people there.
Im sure others will chime in, but I posted two threads about IPO and got many good responses, might be worth it to check those out too.
SG1 Valco 'Berlin' Hokschhaus CGCA BA-1 UNJCH HIT TKA TC
(2x) SG1 Rogue 'Tesla' v Huerta Hof AD UNJ HIC TKA TC