I’ll answer your questions through my own experience, and maybe it will help a bit. I believe I needed to be in a 3rd Order to grow and mature in my faith. I was about 37 when I was invited to a meeting by a friend that I confided in. At that time, my oldest daughter (I had eight children) was a teen and I did not know how to relate to the rebellion she was in. I became more and more anxious about it and wondered what to do about this “bad girl”.
Being in a 3rd Order should not take time away from your main vocation (father/husband). It should enhance that vocation!
For me, the 3rd Order Carmelites began in 1975 and it changed by spiritual outlook, and my prayer life. Being in community with like-minded persons, although very different personalities, is very supportive.
It is true that there may be a wrong time to start, such as when your child was a few months old. But the Holy Spirit does not let up, and the desire to check out 3rd Orders persists!