Potty regression with my 5 month old

Hi all! I have a 5 month Frenchie pup and when we got him at 13 weeks, he was doing really well with going outside. We’d take him out every hour or so and generally, he’d always go and rarely had accidents. However, we are realizing actually we weren’t teaching him potty training, just that when he’s outside, he knows to go. But we weren’t teaching him to ONLY go outside and how to give cues. Now, I’m at a loss as to where to start. He has started to have more accidents in the house and I’m wondering if it’s too late. And tips? TIA!