15 mg of Armour is next to nothing, so I think you're going to want to see your doctor before 3 months... Armour is, typically, increased at 2 week intervals, with testing at 4-6 weeks, as goolarra mentioned... You're probably going to be feeling pretty bad in 3 months...
Do you have current labs you can post, with reference ranges? That will help us see your current status...
Do you have Hashimoto's?
Meds reach full potential in your blood 4-6 weeks after a change. Three month is way too long. When my endo was actively adjusting, I had labs at four weeks and saw him at five.
Most people swallow it. No need to dissolve unless you feel the meds aren't being absorbed properly.