Audio previews should obey the "From current time" option in the preview panel just like normal RAM previews. If they don't and AE still only plays the entire audio it could mean you have a config problem with your audio devices or are working with compressed sources, which require to be fully decoded so AE can do a "mix" to RAM before playing...
I imagine most audio sources are compressed in some fashion, unless it's an original .wav form (which would be heavy).
In my case, I'm also using a .wav file, but it was compressed to some extent.
Still, I'm able to playback audio from the current time position using the "Del" key on the numeric keyboard, but this only plays back audio, not the video.
I'd like to preview both audio and video "from current position" if possible.
After re-reading the keyboard shortcuts list, I'm not sure if it's even possible.
After reloading my project, it now works..
Great...thanks for the help!