depends on how much u play a day.
if u play like 1-2 hour a day and ur doing yaks it will take a month from 70.
note u wont stay there till 99 range,trust me. ull get bored after 2-3 lvls. i recommend u to do green drags 30-40k xp an hour. or greater demons, u make 1 mill per 100k xp:)and ull also get clue scroll lvl3:)