Surprising no-body has actually given useful advice as yet, so in a vein attempt I'll give my two bobs worth, here it goes...
We have a 2.5man tent with 4 poles, in the dry and following setup instructions it takes two of us about 5-8mins to get it up and pegged. The inner part first, the poles inserted, then the fly over the top and peg the whole thing down.
In the rain,

I usually do it by myself (I am the butler and my missus is under shelter somewhere, no not in the Bently!). The tent will inevitably get wet but the idea is to reduce the amount or water inside the sleeping section (the inner part) of the tent.
1) Unfold partly the inner section of the tent and lay it out on the ground ensuring only the ground sheet or external (bit that usually touches the ground) part is exposed.
2) Quickly unfold and lay out the fly over the top of the inner. This way it is protected from getting wet while you do the rest.
3) Prepare all poles and lay them in arms reach.
4) Lift the fly up and while the inner is protected from the rain, unfold it underneath the fly. (this bit takes some dexterity).
(Optional) 5) If there are clips or velco that attaches the inner to the fly, do this now before inserting the poles.
6) Insert the main poles (you may need to put in a peg or two depending on the rain or wind conditions to keep the whole kit from flying away.
7) Insert remaining poles. Once all poles are inserted secure the tent as necessary and adjust the fly.
(now have a

)
In our experience this works pretty well. As we have a vestibule in our tent, we can take off our panniers put them in the vestibule and the only things that are wet is our riding gear...
Tip: If you have to pack away a wet tent, pack the fly and the inner separately so as not to get the inner wet. We use a dry bag for the fly, this way we can put it in our panniers without getting everything else wet. When the sun comes out again, hang everything out to dry. The idea is to keep dry things dry...