
Actually at Crufts he will be able to go in Special Puppy, as at Crufts only the age ceiling is 14 months, they raised it due to dogs under 9 months not being allowed, that left the puppy class with only dogs of born in a 3 month period. Least ways I think that is why they did it, whatever it is 14 months.
As regards entering more than 1 class, this used to be normal practice, but it seems that people now adays want the chance of being in the challenge, so fear entering more than one class in case they win one and get beaten in the second. My view is they would have got beaten in challenge anyway.
I have recently made up my first Champion, and I entered her in two classes at Champ shows, and 5 at our breed show where she won her first CC, mind you by the time we had won 3 classes I wished I hadn't entered them all

My breed can sometimes have small entries in the lower classes, so the reason I enter two is to have more competition. at LKA last year I was second in a class of 3, but then I went on to win the next class which had 9 or 10 exhibits. Also if you have a small class the dog hardly gets a chance to get asclimatised, so sometimes it can perform better in the next class!
In the end it is entirely up to you, but if youare new to showing I would enter Puppy and Junior as this will give you more practice,,and hopefully build your and your exhibits confidence. It will also test the water for when he has to be in Junior at the next show.
Barbara and the Grey Curly Tails.