Roger Stern wrote a story, where Strange moved into the Bleeker Street residence before F.F. #1 ("Doctor Strange: From the Marvel Vault," printed in 2011). He even showed up in a cameo as a mystical master in Marvel The Lost Generation.
The logic being that it would take time to garner the underground reputation he had at the time of his first appearance.
It is also relatively accepted that Strange slowed down his aging with magic. A story in the 80s mentions a doctor remembering him from med-school... which at the time would have been in the 40s.
So, even if that was in 1959, that would have made Strange hovering around 60 at the time.
Hos master was the Ancient One, who was born i the 1430s. If he was training his successor, there is no reason to think he wouldn't have taught him how to slow aging.
There is also no reason to believe that time moved the same way during training.
The age thing comes only after the Ankh of Enduring Life thingy. Before that, he should be aging normally.
Once he's at Bleecker Street (which he gets immediately after "graduating" from the Ancient One), his adventures flow one after another as concurrent with other things in the Marvel Universe at the time. There's really no way to work stories like the one "From the Marvel Vault" or even the Lost Generation. I wish that it were so, because I really like The Lost Generation, but I don't see how.