Also, stay low until close enough to know that collision is not imminent. That will ruin everyone's whole day. Don't panic and don't immediately turn back toward lead. Be careful in this situation when trying to keep lead in sight during the overshoot. You will try to turn across his nose to keep the visual picture if you're not careful.
Depth perception plays a major part, here.
A differential of 20 to 30 knots is fine outside 100 feet, but should not be carried any closer. Using some cross-controls will lessen the amount of power reduction required. Again, always aim for the route position, never directly at lead. This has been a brief discussion of some basic techniques to help you stay out of trouble. Whenever a formation flight is planned, be sure to allow time for a thorough debrief if you are serious about learning how to do it right.