While cutting the project scope and reducing task durations can help you shorten your schedule considerably, you can tighten it further by making critical tasks start earlier than their original start dates. When you can’t cut the scope, and reducing task durations isn’t possible or doesn’t shrink your schedule as much as you want, having tasks start earlier might be your only option.
Depending on your particular situation, you can use some or all of the following methods to have tasks start earlier: