Start with the least effective dose and go from there...it's not good to be on an AI all the time which is why you see a lot of guys on TRT lowering doses, splitting the weekly dose into 2-3 smaller shots, or best yet - going to small daily shots and no AI at all...
That being said it's a moving target...the more free test we have the more available to convert to estrogen. Also the higher a male's body fat there higher the conversion/amount of aromatase will be present.
Cookie cutter advice? Start with 1/2 mg twice a week on 250+mg test and see how you feel... or 1/4mg EOD if you can get them that small but the pharma pills are TINY white round ones and tough to get cut in half accurately much less 4 pieces. Everyone is different though... I've known guys on 1g test a week for a YEAR on no AI and fine...and others on 200mg test a week with HIGH estrogen needing 1mg arim 3x a week to get to mid/high normal estrogen range on blood work...