We will be traveling from Guatemala City to Chichicastenango on Dec 20th, which is one day before the Chichi saint's day -- we expect travel up there to be difficult because of the fiesta and Christmas. Can one make a reservation on a Linea Dorada bus from the States? Does one need a reservation at all? We'll arrive in Guatemala City on 12/18 so will have two days in town. Will that be enough time to make arrangements?