Hello,

Visit at https://admission.ignou.ac.in/changeadmdata/admissionstatusnew.asp, enter login credentials such as enrollment number, programme code, and submit the details, you will be directed to a page where you will find all the important details and one such is admission year and it will clearly specify the session and the year in which you have taken admission, so accordingly you can make assessment when you  have to submit assignments or appear for TEE exam, if your course is semester-wise then you have to do the above mentioned work twice a year with a gap of six months, if it's annual course then once a year you will be required to submit assignments and appear for TEE.