If you played between April 1 and June 30 at any CET property, and if you opted in to get the 50% Spring Bonus tiers, they should have posted to your account now.

You will be getting bonuses on ALL tiers earned, including on bonus tiers.

There is some upper limit, but I'm forgetting what it is.

Anyway, for example, if you played on April 18, earned 5000 tiers, and received 10,000 bonus tiers, then your bonus here will be 7500 (half of 15,000).

You should login to Total Rewards to make sure your bonus is correct, though the site is very slow right now, likely due to everyone doing just that.

Provided you opted in, you should get bonuses retroactively. So if you played on April 2 and opted in on May 13, you will still get bonuses for April 2.

I just verified that I received mine.

BTW, there was no really good optimal way to earn Diamond this way. This is due to the way the regular bonus tiers are structured.

The best I could see doing was to earn 2500 tiers in one day, and then 1500 in another. This would earn you 5000 bonus tiers, and then 1000 bonus tiers. This would take you to 10,000 tiers. Then your spring bonus would take you to 15,000.