It may depend on the context a lot. With different time expressions the same phrase in Russian might require different translation in English (i.e. have slightly different meanings). E.g. 1) Я буду кушать, когда ты придёшь домой = I will be eating when you get home. 2) Я уже покушаю к твоему приходу = I will already have eaten by the time you come. Also consider these, both can be translated in the same way: Во сколько ты будешь кушать в следующий раз? = When are you going to eat next time? Во сколько ты в следующий раз покушаешь? = When are you going to eat next time?

In general, imperfective form of a verb corresponds to future continuous and future perfect continuous, and perfective form corresponds to future simple and future perfect in English.