你好这里用how long提问比较好,因为它是对一段时间进行提问.
下面是how often ,how soon, how long的用法,可以仔细看看就明白了.
how long意为“多久、多长时间”,主要是对一段时间进行提问,答语通常是（for）three days/weeks/months等时间段,它可用于各种时态.
How long do you stay in Beijing every year? 每年你在北京住多久?
How long have they lived here? 他们住在这里有多久了?
—How long were you not at school last year? 去年你多久没上学?
—About two weeks. 约两周.
________________________________________________
how soon意为“还要多久”,是对从某个基本时间到将来某动作结束或某动作发生这段时间提问,常用在一般将来时态的句子中,其答语通常是“in + 一段时间”.
—How soon can you finish the work? 还要多久你能完成这项工作?
—In half an hour. 半小时后.
______________________________________________
how often意为“多久……次、是否经常”,用来提问在某一特定的时间进行某个动作的次数,答语通常是always,usually,often,sometimes,once/twice a day/month等.
—How often do you get to school very early? 你多久早到校一次?
—Usually. 通常.
—How often do you see a film? 你多久看一次电影?
—Once a month. 每月一次.