You can show your Message with a time Delay.
Code:
double delay = 0.0;
Timeout(delay, () => GamePlay.gpHUDLogCenter(null, "LW- Fly a fighter sweep over Dover."));
Timeout(delay += 3.0, () => GamePlay.gpHUDLogCenter(null, "Ju87s leave AY18 for Dover in appr. 15 minutes into mission!"));