Obviously he is an older pup, but you need ot train h8im like a young puppy, as you don't know his history. So that means taking (taking and waiting with him, not putting him out) him outside after every play, feed and sleep, and at least once an hour in between and rewarding him when he goes. It is your job to make sure you get your pup out in time, not his to let you know when he needs to go out. Some dogs never learn to tell you they need to go out unless you teach them to. My older two just hang on until they need to go out, or hanga bout by the door for me to notice. My yongest barks if she needs to go out, and believe me, at 5am int he morning, when SHE thinks it's wake up time, it's no fun!

Providing your vigilant, it may take only a few weeks with an older pup. It might take longer. Every time she wees inside it makes training her harder, and she will need more rewarded outside wees to get the message. Don't tell your pup off if you catch him in the act indoors, although a simple firm but quiet 'no' is Ok, but simly take him outside.

Some pups are trained by a few months old, some are trained by 8 months, some a year, but unless it was longer than that, I wouldn't worry if you're using the above method and avoiding inside wees. Crate training might help things along.