I would say that would take you about a week playing 2-4 hours per day. The problem with estimating dung experience, is that there are so many factors which could affect your rate of exp. Normally I don't do 5:5 dungeons below floor 29, but since you are much lower levelled, I would try and find 5 man teams as much as possible and just do small or medium dungeons. This should increase your exp significantly compared to you trying to solo. I dunged solo from 1-70 and it took quite awhile.
