You're close. I have to head off in a few, so I don't have the time to hit every point - but here's the major ones, and why waiting until later is beneficial for you.
1. Progesterone doesn't convert to estradiol. It's just an agonist, that can tell the hypothalamus that more estradiol is needed. The funny thing is that while the negative feedback loop is engaged (you're correct in that progesterone can signal this too), only the call for more aromatization is sent - LH remains turned off as exogenous androgens themselves trigger the feedback loop. Assuming that there is only tren involved, the amount of estradiol created will actually be quite small, and likely not enough to cause gynecomastia.
2. Prolactin cannot create gynecomastia. Only estradiol or a select few drugs can. This is why 19-nors are often a great compliment or a DHT derivative, as they do not add to the estradiol equation in and of themselves. Prolactin just allows for the breast tissue to lactate, as mentioned.
3. Trenbolone is a special progestin in that it has nutrient partitioning capabilities. Lipolysis is more of a function of this than a thermogenic property - this also means that it can potentially cause cholesterol issues. Tren causes sweats (the leading theory anyway) due to a sympathetic nervous system reaction. It's most noticeable at night, because this is when circadian rhythms dictate our state - which is interrupted by tren.
Loss of ability with cardio has been attributed more to the prostaglandin issues wrecking havoc with alveoli in the lungs, although co2 isn't a terrible guess. I have never seen it elevated in blood testing though. Most AAS does (at higher doses) have this effect (among others) in aldosterone, which I agree, is a part of the blood pressure problem. However, estradiol control is usually the culprit, as elevated e2 causes water retention - > hypertension.
In conclusion, the reason why you're being advised to wait isn't because of your lack of pharmacokinetics or understanding how the HPTA works. It's because tren has a very serious impact on mental stability. Add this to the unique issues that progestins can bring to the table - and you have a recipe for disaster. Knowing how you react on nandrolone first, for example, will help prepare you for some of what tren can bring to the table. Having the ability to inject oneself with a degree of proficiency will also come from experience - which is vitally important to keep from panicking when you first experience "Tren cough". There are just so many things that tren can do, it's really in everyone's best interests to experiment with other compounds, build up some experience (for instance, do you KNOW how much AI you would need for your test dose?) and then you should try trenbolone.
Tren is a fantastic hormone; but if it's not treated with respect, it will very certainly ruin your day.