Looking good! I have always enjoyed assembling a dish and catching the first signal. It never gets old!
It will be extremely difficult to get the panels to form a parabola when attaching them together on an installed mount. Typically, reflectors will be assembled on a perfectly flat surface with the center of the dish supported with a bucket. Once the bolts are lightly snugged, roll the dish onto its back and perform a string test. Once the string tests passes, begin tightening the hardware while monitoring the string contacts.
To see if you need to bring the reflector down to correct the parabola, stretch 3 or 4 strings across the reflector from opposing edges and be sure that all strings lightly touch in the center. If the strings do not lightly contact, the panels are not aligned causing a misshapen parabola. This warped reflector will result in a very poor efficiency with the reflected signals not converging into the feedhorn. It will also be very difficult to accurately track the arc with a poorly shaped parabola.