Leon to Santiago
Hi Steph,
I just walked this very route at the start of April. It got very crowded in the second week as it was Holy Week. On two occasions we had to stay in Hostels as the Albergues were full.
My advice to you would be to firstly not make any set plans, but try to stay in the albergues that are not featured so heavily in the guide books, you may avoid the crowds that way. And be prepared for hot weather. Mind you, as I am from Ireland, all other countries are hotter.
Hope you have a good Camino
Hanleyman