
Castration is an option from six months on dogs primarily for anaesthetic reasons. Doing it asap cuts down many diseases/cancer risks to nearly nil but waiting for a season to pass or the dog to be fully grown has other affects on how the dog will grow/mature vis a vis bone structure.
Seasons can start as young as six months - with many being around the nine month age.
At five months, they will be sleeping less & be playing much more.
The guide to holding a bladder full of urine is an hour for each month. This is less for smaller dogs, however. I found that a two month old CKCS, for example, was looking to go every half hour when she was awake.