Petty much just gonna expand on what's been said first this:
No training during this time you want to develop a bond with your dog. A getting to know your dog period his has been proven to develope fewer handler/dog "issues" with K9 teams, I did not do that with my rescue GSD, I had "problems" but it all worked out in the long run.
I just got a rescued dog – what do I do? | stickydogblog
I had "people "aggression issues you seem to have "fear" issues. Both take time and patience. Both need the same solution your dog needs to look to you for guidance. Your dog should not pick and chose who's a problem that's your job and you need to show him, he can trust you and what normal interactions look like.
Leerburg | Who Pets Your Puppy or Dog
Very similar to this:
Five Golden Rules for Working with Fearful Dogs by Nicole Wilde | Fearfuldogs' Blog
Finally don't screw up your hard work by having a bad encounter, a dog fight at a Dog Park or bad encounter with "I thought my dog was friendly folks" will show your dog that "you" can't protect him!
Leerburg | Dog Parks: Why They Are A Bad Idea
"My" personal belief is that in addition to the obvious possibility of a fight, if your dog runs around out of control with a pack of dogs he learns you don't matter!
I'm sure once you put a lot of time and training into your dog that is most likely not the case but if you put a lot of time in training into your dog why take the risk?
Are Dog Parks a Good Idea for Service Dogs? | Working Like Dogs
Three Dogs Who Shouldn’t Be at the Dog Park or Daycare | Robin Bennett
To start leash work:
My guys were all taught to ignore other dogs and I never put them in a position to be attacked or struck
by another dog. I never had leash reactive dogs but if you do:
Good luck and have fun with your dog.