First of, good for you on the physique abd the upcoming shoot. Second, you wasted so much potential starting tren that early in your cycle history. There is a duck thing as growing to quickly.
About the primo. Primo is a compound that needs to be ran for very long periods of time to see it's true potential. It truly kick in until like week 8. Sometimes longer. Now, yoy will see some benefits far earlier than that, but there is a rather big difference between week 6 and week, say, ten. With this said, if this is as important a photo shoot as you're saying then add it. If it weren't for the shoot then I would say to save it cuz you're already running some awesome compounds, all with such an amazing set of synergistic effects on one another. After you run this primo, be sure to run it again in the future with just test and maybe an oral.
I know you said that you got pre cycle blood work abd will again at the end, but with tren and mast you need to get blood work done mid cycle, as well. Mast and tren are rather harsh on your liver alone, but together it can cause a good amount of damage quickly and you're running a very long cycle of compounds that most people limit to 10-12 weeks. To be honest, if you add the primo you might even want to consider dropping the mast. Be sure that you're running done liver support. Primo is a great drug, but so are mast and tren. The combination of any two of those with test. All 3 would do things I couldn't imagine. The fact that you're using so much gear so soon disappoints me. Like I said, more is not better. You can limit your potential by using stronger compounds too soon or too much gear. It can down regulate receptors, as well abd a plethora of other things dependant upon a array of various variables.
If I were in your shoes and knew that I had a big shoot coming up, I would have began with test and primo (test PROP@300/week and primo@800-1200/week and some var@75-125/day) then I would have added the tren and mast for these 8 weeks while continuing the primo(tren ACE@525-700/week and mast @600-800/week). That would have yielded done impressive slabs of meat. Whatever you decide, good luck, congrats, abd stay safe!