Comment by colechristensen

For a cold start, you have to wait 30 seconds for the whole ephemeris data to be broadcast unless you have another data path getting you A-GPS data. (it's literally just broadcast that slowly)

You can still get pretty accurate time (microseconds) with the GPS almanac which is broadcast over ~15 minutes and only updated every few months.

Doing really fast time acquisition isn't a hard problem but it's a hardware problem, you can't really change how an ordinary GPS receiver operates, you have to have a custom receiver.