Lay it out roughly where you want it then two options:
1. Put all the poles through and secure then into the fly. Then pop a couple of pegs into the back end of the tent and, with a friend on the other side, lift and pull the thing out as if extending an accordion. Peg in the other end.
2. The Cross Camping method. Find on YouTube. Lay it out and peg in the four corners not too tightly. Leave the doors open so no airlock. Put the most central pole through and fix it into the fly at either side. It will be basically standing now so someone else can stay putting things inside for example. Work outwards and do the other poles. This way is quite handy if you're alone or it's windy or rainy.