Board Thread:Theories and Speculation/@comment-35448581-20160502192848/@comment-734582-20160507165742

We don't really know when Hamura and Hagoromo's Dojutsu kicked in. For all we know, Hagoromo awoke Rinnegan the day before battle and Hamura the day after. So it doesn't have to be a big deal that Hamura got Tenseigan later.

The alternative is that Hagoromo awoke his Dojutsu first and developed physical powers later, and Hamura vice versa.