Call CTO (contracted travel office) and request that your ticket be purchased earlier than the normal 3 business day ticketing timeframe. You can do this if, for whatever reason - going on leave, other trips, etc - you need to have ticketing completed sooner.

I've never had a problem with it. The only holdup might be that your orders would have to be showing as "Approved" by the approving official before CTO can process the ticket purchase. So it probably wouldn't be possible to do it immediately after DTS shows "CTO Booked". Though in my office the AO usually approves my orders within a day or two.

However I've never tried to get the purchase done prior to Approval so you could give it a shot and see.