You could definitely have a house built between now and christmas. Honestly a wooden house can be built within a month. A concrete house takes longer but if your funding is timed correctly and your builder is professional enough to be able to plan the shipments in a timely fashion a 6 month build is well within the realms of possibility.

My house took 8 months to build, about 4,000 sq ft. But we had a major medical emergency during that period when we couldn't focus on the house a about a month.

I can suggest some builders if you need some contacts. Send me a PM.