Hello Steo! Welcome to the forum!
I guess you don't play on Xbox, do you? The point is that in the Xbox version you can jump a little bit higher than in the other versions. The difference is hardly noticeable, but it's still enough to make this jump (and maybe a few other jumps e.g. in SBTC part 2) impossible on the other consoles. Cut once wrote that the order of the jumping height is: Xbox > GC > PS2 > PC.
If you want to give it a shot, you might try a superjump to reach the vortex at the beginning. You can see one
here.
However performing this glitch is probably quite annoying when you try it for the first time. So, if you don't want to put too much effort into it, you can simply play the beginning without the vortex. You'll be still able to get a nice score in the end then. Good luck!