SP Jain Aptitude test is conducted four times a year usually in the months of April, May, June & July. Before applying for the test you should check the eligibility criteria, as per the eligibility criteria, you should have a graduation degree in any discipline from a recognized university also if you are in your final year of graduation.

So, according to your situation you can give SPJAT in July 2019 at the earliest.

Hope this will help you :)