Anything under 1 year - IMO - is still a pup. You are lucky to find an older one. Potty trained, and you have a better idea of what it will somewhat look like as an adult. So much better!! All shots too. Wow! Not so fagile as a 2 month old - Persoanaly, I would never buy a 2 month old - still has socializing to do. And a 5 month - you do not need to worry so much about hypoglycemia (low blood sugar). If he is what you want - I would jump at the chance and not let the older age stop you. It is a plus!!
