That really depends on the complexity of the app/environment in question and on the definition of “up to speed”. If you consider it sufficient that the hire can

That really depends on the complexity of the app/environment in question and on the definition of “up to speed”. If you consider it sufficient that the hire can contribute code changes, then a few weeks is probably enough. If having a good model of a moderately complex environment is the goal, a few month doesn’t sound off.