My Glen Terrier was 8 months old when I got him. He'd been kept outside in kennels with the breeders other glens. She warned me he wouldn't be house trained.
When we got him home he peed as soon as he put his paws on carpet (I think he must have thought he was on grass). He also panted a great deal inside as I guess he was used to cooler temps. After a couple of days he aclimatised to the temps in the house and was fine.
Potty training took a week it was very similar to puppy training Monty. Owain was used to going whenever the urge took him but the difference was he would go behind the furniture or in a corner, not as Monty who would go where ever he was at the time. A few days of careful watching, a firm no when caught doing it in the house and lots of praise when doing it outside paid off and he was soon trained.
Looking back now I'm not sure who was easier to train. I constantly watched my 7week puppy and he was taken outside about every 30 minutes apart from when he was sleeping. With Owain, still a puppy but older the signs were easier to spot.
Good luck as long as you are consistent I'm sure you'll have few problems.