MBB Undergrad recruitment in Singapore?

Hello I am an undergraduate student from one of the top 3 universities in Singapore. I wish to work in one of the MBB firms in the Singapore office after graduation and I was hoping to gather some expert insights on the following:

1. What time of the year is the recruitment done for BA/Associate roles at McK and BCG respectively? (I am asking because I might graduate off-cycle in December instead of May. I know their applications are open year round, but I think there has to be a timeline they probably follow.)

2. How would recruitment be affected by the virus situation for fresh graduates?

3. Is there a PST/Potential test etc for these three firms in the Singapore office? (Generally, I've never heard any of my seniors talk about the test but directly discuss the case intereview, which is why I think that there is no test here.)

4. Assuming recruitment happens in October, when would you ask for a referral to be sent?

Please feel free to answer even one question out of the four. Thank you so much!