You can boost grab after up to 3 frames of dash attack. For Sheik, it is important to use all 3 frames to get the furthest boost. Fox/Falco have a dust graphical effect on frame 3, so you can tell when it is the perfect length. Just requesting a code to add a similar dust effect to frame 3 of sheiks dash attack for a subtle way to tell when you get the perfect boost grab while playing Sheik.