How do i make a floating projectile and add vector

So I made an animated mob with the geckolib plugin and wanted to add a cool attack

Basically the mob moves back and then starts charging the attack which spawn an orb (which is a projectile ive already created) at the 15th tick and throws it at the 25th tick

I managed to get the synchronization right using an nbt timer but I cant figure out how to make the projectile spawn without moving and then apply a vector to it to make it move in a straight line towards the direction the mob is facing in

This is my procedure (its in the On entity tick update trigger): 

(link if the image doesnt work): https://imgur.com/a/dLoIijQ