As of SEOW v3.2, commanders are able to specify a delay time before their aircraft spawn in the mission. The delay is specified by clicking on the ETA link in the waypoint listing in the left column as waypoints are created for a flight. Only the takeoff waypoint has a live ETA link. Click on this and specify a delay period in minutes, e.g. 10 minutes. At the end of the 10th minute, the flight will appear in takeoff position at the relevant runway or off map spawn location, and will proceed on its mission as planned.
Clearly this brings some nice features into the game, but it also has significant drawbacks.
You can now plot your flights in waves. This is especially good for carrier campaigns where flight deck room is limited. Get your fighters up first, then take your bombers off 8 minutes later.
Where fuel endurance is low, you can delay extra flights considerably, allowing you to stage your CAPs over a long period of time.
All delayed flights will be AI Only. This is an IL-2 limitation.
Spawning of new flights into the mission may cause pausing.
It is the commander's responsibility to ensure that runways are CLEAR when new flights are due to spawn in. Collisions will occur if planes are landing whilst new flights are spawning in.