Before my CF in 2022, I dreaded getting to Sarria based on all the stories I'd heard about crowds, and I have to admit those fears were not assauged on the way into town when I encountered the first of (many, many) school groups wandering the streets. (My calendar tells me that I arrived in Sarria on June 7, so around the same time you're thinking of being there.)
But Sarria ended up being one of my favorite stops on my entire walk, mainly because of two memorable meals (at
Matias Locanda and at a vegetarian café near
Peregrinoteca that I can't seem to locate on Google Maps anymore) and an absolutely fantastic stay at
La Casona de Sarria, which I can't recommend highly enough. And some of the folks who started their walk in Sarria became my closest companions en route to Santiago and remain good friends to this day.
Of course, your mileage may vary, and if you're looking for absolute peace and quiet maybe walking another five day stretch would be a better option. But I wouldn't rule out the Sarria to Santiago route just because of the things you've heard about it (including my own report.) Like the Meseta — another stretch of the Camino that some recommend avoiding for whatever reason (and another part that I loved), I think It's worth experiencing firsthand yourself.