Advice on potty training my puppy

Hi everyone! So my husband and I are getting our very first puppy! I have a couple of years experience training dogs (nothing professional just minor things for family pets) and I am a little confused with how to tackle our specific needs. Our boy will be around 7 weeks, he will only have his first round of shots at the time we get him. It is super important that we are able to train him to go outside and not just on pads. We have pads available, both reusable and the disposable types. But, the issue that I’m noticing is we don’t have a fenced yard. We live in a rural part of our road but I know for a fact we have had adult dogs from down the road that at least walk on our yard. ( not frequently, but once or twice in the last year) So is there any way I could take my boy outside to go without risking him to Parvo or should we stick with pads indoors until his last round of shots? And if we do have to resort to pads inside until his shots are complete, will we be able to retrain him to just going outside since he may grow accustomed to going on the pads?

(And please no suggestions like getting a fenced yard or shock collars or anything like wise, we just want to use a leash or harness and take him out when he needs to go by alerting using a bell 🙂 )

Thanks in advance!