I had a lot of baggage from a previous dog owning experience when we got Molo - including seeing my previous dog jump off a railway bridge to avoid an oncoming train, losing her within spitting distance of the M25 and ultimately, her tragically killing a domestic cat that was in the field we were exercising in
- and so I didn't let Molo off lead when he was a young puppy - and it is my very
biggest regret
It took me over a year of long-line training when he was older to undo the damage that my (understandable) paranoia had caused.....time I would far rather have spent enjoying my young dog, rather than feeling as if I would never be able to let him off
I know it is scary, but try to find somewhere secure - if it makes you feel more comfortable then pay for use of a fenced paddock or tennis court - and let him off as soon as you possibly can.
Don't mistake a puppies desire to be close to you with recall though - make sure that you do "train" recall to a whistle or command, even though he may happily stay by your side at the moment, in a few months he may go through a challenging phase and a well trained and established recall will be impossible to train, then