Before you go assuming 8x8 is overkill you need to create a drawing of the frame and have the frame design checked for engineering.
Do you know the snow load for that area?
What about wind load?
These things have to be taken into consideration before you start cutting timbers.
You can cut timbers now, but unless they are stored properly then they may move some while waiting to be worked on or shipped.
You can cut the joints first if you want to. Every little bit helps to reduce the overall weight of the timbers as this might effect the shipping cost.
You can begin working green timbers as soon as your design is finalized. There isn't much value in waiting for them to dry out much, as it will take years for an 8x8 to dry to the center.
Hope this helps.
Jim Rogers
