I've been tearing my hair out since getting the Apollo, struggling with latency in one form or another.
I've been trying to sync up my Arturia arpeggiator, and also their Beatstep.
I'm getting the same 'early' problem.
There's an old article about how Logic 9 handles latency which still applies I reckon.
https://help.apple.com/logicpro/mac/9.1.6/en/logicpro/usermanual/index.html#chapter=41%26section=3%26tasks=true
While Logic is busy compensating for the plugins, calculating delay for all the audio parts so it all syncs up, the starting point for the whole track gradually gets pushed further and further on, though we don't see it. Unfortunately it doesn't also push the MIDI start time, leaving us with an apparently early MIDI trigger.
Switching the plugin compensation mode to 'Software Instruments and Tracks' actually gets it closer when monitoring, and in playback it should be bang on. Make sure you switch back the plugin compensation mode to 'All' when playing back.
This is however an imperfect workaround, instruments which are processed more than lightly will play back out of sync while in Software Instruments and Tracks mode, which is infuritating. Have to go muting things just so you can play along.
The latency issue in general with Apollo is driving me nuts. Just splashed out on a brand new Mac Pro 3.5Ghz 6 Core with 64Gb RAM, with Thunderbolt Apollo, Display and Drives. I couldn't believe it when I had to start fanny around with latency settings.
At the moment, I was better off before I got the damned Apollo. Doing TV composing, you have to be able to mix a trackm but then go back to it on a rolling basis for additional recording and edits. I'm beginning to think UAD was a mistake.
I'm keen to hear other fixes or settings.