Fever time PvP % delay?

Logged in and did some PvP. Took me 6 games before fever time bonus of 50% kicked in. Is there a required amount of matches before it works? This happens everytime for me. Sometimes its after 3 matches, sometimes its 5. Now it was 6 matches until i started to get the bonus.

Anyone have any info on how it works? I know it starts at a certain time during the weekend, which im always in