It doesn't matter how fast you approach this one unless you are doing a rock' roll slide. What matters is that when your bringing it back in you adequately pump while going back into the ramp.

Get more comfortable landing it. When you are confident coming down you will need to still regularly pump to gain speed back down the ramp. Since you are at a decent stall when this trick is performed, speed of the approach matters very little.

Go faster, duh

Oops I meant when I get out of the rock n roll I don't have any speed

Go faster, lift trucks and turn quickly

take some speed and turn fast after you rock to fakie

Harry and Nate have your answers. Keep practicing 🔥

You should get speed from rolling back down the ramp try pumping on your way down

Pump at the bottom