Shuttles from Casa Verde Tours depart at 5 AM (with connection to Lanquin from Antigua) and 9:30 AM. Also in Antigua, you can also pick up a shuttle to anywhere in Guatemala as well as Mexico and points south.
Casa Verde Tours transportation to Antigua is only Q40 (others charge Q60) right now. Q90 to the capital. They also have the best shuttle to the Semuc Champey area, a 5 AM departure that arrives in Lanquin at 4 PM.
The Casa Verde shuttles depart from in front of Alegre Pub in the zone viva for Antigua, the capital and Lanquin at 5 AM and 8 AM.