Can I fill the exam form and send it before submitting assignments for the IGNOU distance course?

No. You cannot do that. There is a proper procedure that everyone needs to follow regarding the submission of assignments at IGNOU.

Step 1: Submit all your assignments at your study center. Also, make photocopies of your assignments before submitting them. These photocopies along with the signatures will be proof of your submission of assignments. 

Step 2: After submitting all your assignments fill your exam form. Get the signature of your study center coordinator at the back of the form. 

Step 3: When you are done submitting, go to your regional center m. Here you are required to submit your TEE form ( Term End Examination). Fill out the receipt they give and submit it along with the demand draft and TEE form. 

You will get the signed receipt back. Keep this safely with you for future use.