I love cassia. It has really helped with strengthening my hair. I add my conditioner, oil and a touch of water to it, leave it on for an hour and my hair feels like it came back to life. It's a little messy, but worth it. I like to use cassia once a month, usually around the beginning unless I get really busy then I use it in the middle of the month. It's safe to use any time so it doesn't really matter if it's used at the beginning or the middle or even the end of each month. Some people like to use it every two weeks.
I plan to use this while stretching. I like how it leaves the hair feeling so strong.