First option: reduce scope
The cheapest way to hit an earlier date is usually to ship less, well, rather than everything, hurriedly.
Second option: reschedule
If another project can move without harming that client, we ask them. We never bump one client for another silently.
Third option: expedited booking
Where genuine displacement is involved, an expedited rate applies because other committed work has to be compensated for.
What we will not do
Promise a date we cannot hold. An accepted rush that fails is worse for you than a declined one.