I've been using LCY since the day it opened. Great airport. I generally assume that I'm on the DLR from domestic within 10 minutes of doors open, you can often be in central London at the advertised arrival time into LCY, since they tend to pad the schedules a bit.

Some great advice up top, the only point I would add is that the DLR has a different approach to Oysters, and you need to touch in. The touch points are a little hidden, on both sides of the central column by the ticketing area. You have to walk around this column to get to the platform, so look towards that column. Contactless bank cards work fine there. If changing at Canning Town on to the Jubilee, no need to do anything there, but if leaving the DLR station rather than changing you need to touch out too.

The only downside, and it drives me nearly insane, is the "local accent" on the DLR: "The next storp eeesss: [pause] Puntun Dawrkk", oh Jesus wept.