Reworking Potty Training in an Apartment

I just brought home my 6-month-old miniature pinscher about 6 days ago and I think I messed up his potty training by doing too much too soon. He is very timid and seems to be going through a fear period right now while he is adjusting to his new home. Thats fine and I understand this can happen, but he was previously a mostly outdoor dog before I got him and he seems terrified of everything outside. When I was trying to potty train him the first first few days I would take him down stairs and let him walk on his harness (he does pretty well) but he will not go pee outside. He poops outside usually if it's warm enough and we've walked enough, but he will not pee. I give him plenty of access to water but he will hold it all day and then just pee inside on a pad near the door where he had his first accident.

My question is, now that I've bought a turf pad for my apartment balcony is it better that I regress him and only take him out on the patio for potty instead of walks/going downstairs?