While my hairline was fine, and had no loss in the crown I was noticing my temples going back further and further, and I was always finding hair in the sink after brushing my teeth or whatever. I decided that something needed to be done, so I started Finasteride a week or so after E to completely stop any hair loss. I did shed a bit in the crown but not to a point where it was visibly noticeable. That stopped after about 2 months and now my temples are even seeing quite a bit of miniaturized hair where there was absolutely no hair (which... regrowth on the frontal corners is rare). I can also see a ton of new growth (terminal strands) just behind the hairline and I see quite a bit of 2-3 inch long strands coming from the crown. Now I almost never see stray hairs unless I look for them on the floor or something, my dryer has no hair in it, and I can go a week without shampooing my hair and only lose about 20-30 strands (I shampoo twice and condition my hair when I do).
Avodart is more powerful, but it does the same thing. Also, even if you don't have hair loss I would still think about taking a DHT blocker. DHT can really interfere with estradiol as it is many times more potent than testosterone.