Immediately after the destruction of the 5th...

[Olefin]

Some of it will come down to how much chaos you inflict on the way out - my group caused a lot of chaos on the way out including taking out a supply dump, freeing a bunch of POW's (who joined us) and taking out the Army HQ - we had a big group and got lucky with our rolls so we had the equipment and personnel to do that kind of damage

but even a small group should be able to cause some chaos and delay pursuit long enough for them to get completely clear before any organized group can come after them