I will start in early June. My only concern is that in the next few years the Sarria route becomes more popular, so I was thinking of doing it and getting that part out of the way before too many crowds ruin any experience.
I'm also 60 so wondering if Sarria would be a better initiation for the first time? Thoughts?
I really think that the danger of crowds is oversold. I walked the busiest part of this section last year, at the busiest time of year and didn't find crowds overwhelming. In fact, I had plenty of solitude and mostly had only one or two other pilgrims in sight. That said, I was staying "in between", as J Willhaus suggests.
The challenge with getting that part "out of the way" is that it is the last part of any
Camino Frances, the part that leads directly into Santiago and the cathedral.
In general, my advice would vary depending on how much time you have, whether you think you are likely to return, and what is drawing you to the
Camino Frances in particular. If you are drawn to the Frances and are confident you might return, there is nothing wrong with starting wherever you consider the Frances to start and walking as far as you want this trip and resuming from where you left off on a future trip. Just be sure that you get your credential stamped where you stopped and stamped again there when you resume. If you are not so drawn in particular to the Frances, or are not sure that you are going to return, it might make sense to pick another Camino where you can feel like you've walked the "whole" Camino and make it into Santiago. If you really want to walk the Frances, however, there is nothing wrong with figuring out how much time you have, and how far you think you can walk, and starting the Frances that far from Santiago (giving yourself a bit of a cushion, of course).
Based on my experiences on Caminos, and those of many pilgrims I met, I wouldn't consider your age an important factor (speaking as someone who is also 60).