Is it okay for someone to bump their own post?
It honestly depends on what the thread or topic is. Even though there is a rule regarding bumping old threads, and multi-bumping/posting. This rule generally covers the 'black and white' side of things. However, I can explain the more grey areas for you, as sometimes bumping threads and multi-bumping/posting is okay.
If a topic is still relevant, such as discussions (Game Discussions, Forum Discussions, Input/Ideas etc), then a user is more than welcome to share their opinion/views on such topics instead of creating a duplicate thread. Though, since you're asking if it's okay for someone to bump their own post, then they're free to as it's theirs. The only time you're not really permitted to bump a thread is if the thread is inactive, no longer relevant, is not necessary to, and/or if the thread creator is no longer active.
One thing I should point out is that it's also fine to multi-bump threads of your own, as long as there's a valid reason. Such as posting about an update, or an update to your original post, or bumping a request thread after a while if it's not getting the right attention. For example; you're requesting a preset, but the thread hasn't been posted after a few days and other request threads have been made, bumping your thread further down. This is when it's fine to bump your thread to the top, as you're needing/wanting something, and you need/want to catch the eye of someone who can help you.
Hopefully this clears things up and answers the grey areas. If you ever need more help regarding this, then you're welcome to message a Staff Member and ask them whether or not it is okay to bump a thread if you're unsure!