Honestly, I don't know when the TYBW manga starts. But you could search manga databases or ask in manga enthusiast communities to get the details you need.
The TYBW arc's starting chapter isn't a straightforward answer. It could be different based on the manga version and region. I suggest looking at dedicated manga websites or asking fellow manga enthusiasts for the exact chapter.
I'd suggest checking manga forums or dedicated Bleach fan sites. They often have detailed breakdowns and recommendations on where to pick up after a specific part. Sometimes, the author or official sources might provide cues as well.
To create believable characters, study the original Ichigo's personality traits. He's brave, determined, and has a strong sense of justice. For fem Ichigo, you can keep some of those core traits but also add some feminine touches. For example, she might be more in touch with her emotions but still be as fierce in battle as Ichigo.