The version bump should be done in
parallel with the very first change to the repo. If the user
fixes a typo, and the component has not yet been version-bumped,
then it must now be version-bumped, during that very first
commit.
But of course repo-owners have the right to simply bump
everything immediately after the branch if they feel safer doing
it that way... if they feel like they need to so they don't
forget to do it later.
In general, making it a mandatory step just after a release makes
sure no-one forgets it later. The worst case is the next builds for
that stream are not used: versions got bump without added value.