Low Thyroid, my hair started to fall out, and my skin...

Hi Everyone,
A couple monthes ago my hair started to fall out, and my skin got very dry I was also more tired then usual. My mom is a doctor so she ordered me a blood test that came back on the low side of normal. So I started to take armour thyroid, and I am starting to feel better although I have only been on it for 1 week. But my question is how long does it take usually for hair to stop falling out and skin to not be dry?
Thanks so much!!