The last couple of years new items have shown up first on the Estes website on the “Coming Soon” page (but not available for order), then when they go live for ordering they move to the “New” page, then, after some unknown timeframe or condition occurs, they start showing up at the online and brick-and-mortar retail level, then finally, on the discounter websites like Belleville Hobby and AC Supply. Last year with the release of the Skylab Saturn V and Saturn 1b that scenario didn’t follow the usual pattern, with seemingly random online retailers offering pre-orders, some discounters having the Saturns available before it went live on the Estes website, etc...
So long answer short at this time, 2:20PM EST, Monday January 18 2021 none of the usual sources for Estes rockets that I know of has the new #9721 PSII 3” Der Big Red Max available for order.