Hey mate, welcome to the forum. I have similar experience with a MILF from my gym too altho shes probably only 7 years older than me but she has a body of a 17 year old haha.

This is my experience: I started with building a rapport/attraction. I was talking to her on/off for at least 1 month before it starting getting deeper and she started being open with me more about herself. Building the attraction is important imho. Then I move on to texting her reqularly and then inviting her to a club (salsa) with my friends. Then one saturday evening she texted me asking to take her out to a club. I duly obliged and the rest was history... ;-)

Depending on what you want but from the very beginning I made a point that Im happy being single and wont start a relationship with anyone so she knows that im not after a relationship. If shes comfortable with that, she will carry on talking to you and you can take it from there...!

HTH. Much Success!