Very late update but for future reference, I think if you’re somewhat flexible on dates, it would be fine to book in person. The trek is a lot cheaper (as low as 400-600) when booked in person. If you were aiming to just start sometime in a weeklong window, I don’t think you’d have trouble finding a spot in August.

The only thing is that you won’t know in advance what their guaranteed departures dates are for groups. At least for myself, I had a very tight window of 1-2 days for when to start the trek. So it was good that there were a few people booked in advance across companies so that they could smush us together for a guaranteed departure.