I really hope I've just figured this out.
After her show in Puerto Rico today, she doesn't have anymore shows until October 16, in Australia. In 2008, she released IIWAB and SL on October 12, so what if she releases her first single for this album around the same time? That would allow her to start performing the new single when she starts in Australia a few days later, as well as (hopefully) topping the charts in the US, simultaneously.
Then, when her Australia tour is over 3 weeks later (Nov 9), she has no other shows for 3 weeks, on November 30 in Canada. She released IASF on November 14, 2008. So that would give her 3 weeks (Nov 9-30) to promote both the new single, as well as her new album, should she release #5 around that same time. Then, when she finishes up her final North America leg, she'll be able to both promote the album that way, as well as making appearances on TV, in the lead-up to the Christmas shopping season. Speaking of...
X-Factor airs on Wednesdays and Thursdays in the US, from Los Angeles. Bey has an LA show on December 3, which is a Tuesday. She'll likely be in LA the next couple of days too, so she could easily appear on XF. And who is a judge on XF? Kelly Rowland. We all know how much Simon Cowell would love to try and boost ratings by promising a reunion of the two original members of DC, as well as a Beyonce performance. This could also give her an opportunity to perform on shows like the Tonight Show, since she'll be in LA with 2 days of no concerts. Amazing promo.
And just two weeks after that, her tour will be over, and she can do whatever she wants for promo, since she'll have plenty of free time, as compared to now.