BIAB calls such events "pushes". If you go to Help >> Index when next in BIAB and search for "pushes", you will get a pretty comprehensive explanation. Essentially, if you right-click on the chord you want to have coming in early, then choose "Chord settings", you will be taken to a dialogue box that will allow you to invoke these pushes.

Alternatively, you can simply type ^ (shift+6) before a chord for an 1/8 note push or ^^ for a 1/16 note push. For example, if you type ^C, this means that the C chord will be played 1/8 note before the beat on which it is notated.

Hope that helps,
Noel