I'm going to say the opposite. NPC before recruitment.

Obviously running one or two NPCs is more work for you, but in all the games I've been in on GitP, recruitment is very much a gamble. You'll probably get plenty of applications, but people seem to ghost distressingly often, and then we're back to square one.

Using NPCs also has the advantage that it doesn't have to be the same characters all the time. Depending on the style of game, DrK can introduce and retire NPCs as needed to give our group the necessary skill set to deal with the adventures ahead.