Tom wrote: I'm not too familiar with your climate, but if you get the pots up off the ground in the spring, more heat will get into the soil in the pot, allowing earlier starts. The darker ground inside will also collect more heat. If you want to temper the heat of the day and the cool of the night, store a couple black plastic trash cans inside and fill them with water. They will act as a heat sink.
The little house is only 6 by 8, but still has lots of room. Across the back I put two 32 gallon trash cans (on sale at Lowe's for $10 each). I filled them with water and then made a bench with 6 foot fence slats.
An additional shelf held several pots and we had stands for this and that. We covered the floor with bark. It smells nice and may act as additional insulation. I've been measuring temps of the air, soil and water and so far all is working as expected.
We saved space for spring starts - that's were the chair is. For now its sunny, warm and humid during the day. A nice space to sit for a bit. Maybe a cigar and a glass of good American whiskey?