I have found a lot of ppl have different ideas of what humidity should be. I prefer to keep it around 40% until day 18 and then keep it around 60%. Some ppl like it higher, some like it lower. And most ppl KNOW they are doing it the correct way. I guess you really just have to do what you think is best. And it does depend upon your climate also.
Between 30% an 40% the first 18 days. On day 18 start trying to keep it between 60% an 70%. After you do it a few times you'll find what you like better.