I guess it depends where you are going to be. Places like La Paz and Potosi are very high up so the adaptation will be longer. Sucre, on the other hand, is "only" 2000 metres or so above sea - level so shouldn't take too long to acclimatise. It's also a very pleasant place, or at least was 10 years ago! No altitude worries in Santa Cruz, but a humid, tropical climate.