That's no problem. Actually having transfers "running late" adds a little sense of realism. Rather than fixing the problem (checking transfers more frequently, or having an event queue), you could simply change the phrasing to show it's late. For example, rather than showing "ETA: 0:-5" at 0840h, since we know the next transfer-complete-check will happen at 0900h and the transfer was supposed to arrive at 0835h, you could print "ETA: 0:20 (delayed 25 minutes due to weather)" or similar. Not important in the slightest, but could add a small amount of fun realism.