Yes, if you are uairing as soon as possible you will be able to dj afterward. If you can sh uair (bair works too), dj waveland on one of the platforms on DL64 you're doing it right. The timing window is easier on the waveland at PS/BF/YS since the platforms are lower but you still have to learn to hit uair on the first available frame.
Baiting approaches from opponents...
Full hop aerials.... input the aerial as soon as you've held jump long enough to make it a full jump. Once they see you jump and fair, or especially dair, most people think that you're about land and they'll be able to punish your lag... they don't know that you can dj after the dair is over but before you've hit the ground and punish/evade as necessary.
Mixing up platform/edge work.... lots of players react as soon as they see ganon jump for a platform. You can bait stuff by jumping up to a platform and wavelanding in place, for example. If they were expecting an immediate waveland > aerial approach and covered that option, you can now run off or drop through the platform and punish. Same thing with them expecting a ledgedash... ledgehop and fair, invincible jab, grab, etc. If they are expecting the ledge dash. Then when they start crowding the edge more mix in some rolls/RLD/run off dj bair's, etc.
Shorthop aerials also... the retreating uair can get people to approach in the same sense as the fulljump aerials can, then you have the dj + punishment option if they go in.
Upsmash... people still overestimate the cooldown time and approach trying to punish it, and they eat your jab.
Edge cancels... don't get repetitive or you'll lose your ability to surprise people but obviously they see a seemingly poorly spaced attack and then BOOM. got em.
Basically any well placed aerial can bait also. You need to be aware of your opponent's options in any given situation, so that you have an idea of what's safe and what isn't. Throw stuff out that is right on the line of being punishable, and see when he himself draws the line and tries to go in and take advantage of what he thinks is a free hit. Stuff that normally wouldn't be safe at all (but it is safe, because they're in lag or something) really tends to bring them in.