Rookie pirates tend to move forward by following a log pose. The grand line is a "natural trainer" based on the assumption that those pirates are actually moving forward rather than sideways and backwards. Jaya and Skypeia are basically the same spot.
I'm not even claiming to know what happened. I just think it's more likely that Bellamy found his conviction sooner rather than later.
actually,if you follow the logpose (and you have to) you move forward that you want it or not.
every route has its islands,islands that you have to do in order like levels in a videogame,so even if their location is similiar,or even if you are not moving towards the red line but sideways,you are still following the same route,that will eventually brough you to the red line..the two alternatives are an eternal pose (which are rare),or not following the logpose (which means that you probably get lost).
if bellamy got to skypiea through the high west,it doesn't matter if jaya is under skypiea because he didn't use the knock up stream (remember?if you use the knock up stream there are two possible outcomes,all die or all live…bellamy is alive,and he is a devil fruit user that couldn't survive if his ship was broken by the current),but another entrance that is far away from jaya (gan forr said that there are at least two "registration" between the high west and skpiea),so he indeed moved forward.