September 24th is exactly 90 days. I would suggest verifying if the option is available on September 24th, and if it is, submit it right away. Until the option is available, EVGA will likely not make an official announcement, so make sure to check back Sept 24th.

They typically only add one card, which is the base model or very close to base model, and if they follow with historical trend, you will have one option, and that will be what you can get.

The step up program is not a requirement and is not supported by NVidia, so it is 100% up to EVGA when they list and what they list as options. If your step up window ends the 24th, and the step ups are enabled the 24th, you will have to decide whether to jump in the step up queue or not. The 25th you will not have the option, and EVGA will not back date it for you. It is a strict 90 day window. Again, no other company even gives this option, so it is a very nice thing of EVGA to continue the program when they have very few reasons to. Anyone that bought from another company will have to eat the loss of their money that they spent, so imagine how they feel.

You can extend the warranty, not the step up window which is a flat 90 days. You also cannot enter the que early and "wait" for the 3000 series cards because they are not currently available. As was suggested, come back on the 24th and see if they have added a RTX 3000 series card to the step up que.