Good luck to you and I don't have much to add except I am a gentleman over 60 who will be starting a new company within the next year.
This is not very common either but the growth potential is actually so much better than when I was younger and less experienced. It's possible to stack all the cards in that direction for more decades than many high-performers have even been alive, much less adults.
Sounds like you have a good media plan and it may take longer to round up the critical mass of ladies so the media sessions may need to stand the test of time more than expected. I would want lots of excess footage and hold onto it, to enable later crafting the shorts to be as engaging and complementary to newer eventual participants too. Also maybe want to have a differently edited offering a year later to extend appeal in an unforeseen direction.
You may need to reach out to women who are actually grandmas but are not 55 yet, that's a lot of ambition right there. Or go far afield for some non-digital businesswomen especially if their story is inspiring or dazzling in such a way that really keeps people interested.
Now something that not everybody is ready for is how does a company started after "retirement" stack up to a bright young startup with many more decades ahead of them?
For one thing it's going to happen a lot faster plus be order(s) of magnitude less risk. Senior citizens have had enough time to work this out so that partners do way better than they would when younger.