Let me point out why you should NOT monitor nor use CM as any kind of indicator. Firstly you shouldn't be sticking things in your vagina to check, you can introduce infection, no matter how clean or careful you are, which could later lead to blocked tubes. Secondly ther are the standards for what is idea, but thats in no means a necessary for conception. Also the most accurate indicators are not CM but temping, bloodwork, OPKs and the like.
Traditionally a mucous plug forms after conception to cover the cervix and prevent infection into the vagina during pregnancy but that is not in early pregnancy, only in later stages of pregnancy. That being said mucous build up can occur inside the vagina and is a common cause of fallopian tube blockage. So mucous yes, but a plug not necessarily. There are multiple types of cervical mucous ranging from thing and watery to lotiony, with or without some clumps to clear, white, slightly yellow (not necessarily an indicator of infection) and so on. whats important is that there is no foul odor or greenish color as well as excessive lumps which are other problems which should be taken care of.
Fertile mucous in and of itself is NOT stick but is slippery and stretchy.
But dont quote me on anything, this is just research of a vehement kind lol