When I started HRT I only took spironolactone for a week. I didn't have an immediate need to crush my testosterone levels and being a minimalist who already had problems regulating electrolytes, I saw no immediate need.
At barely a month in it was clear I was getting feminization at a rate I was happy with and my emotional balance was amazing so I stayed that course until my first blood tests at 4 months in. Results were rock bottom T levels <~ 13ng/dl and since then because my E levels were high, my E dosage has been halved twice and still testosterone was <~ 20ng.
It's different for everyone, endocrinology is complicated so I wouldn't count on T coming up if even you remove Spiro. Anecdotally, injected estradiol suppresses better than oral administration and obviously, I at least didn't need high doses to achieve full suppression.
