I am a final year Ph.D. collaborating with people in my lab (Biomedical) and spent more than a year on this side project which is not part of my thesis research. My results combined with some calculations (which I also performed a bit) from a colleague (research associate) can make up a story and we decided to write the manuscript. In the beginning, we agree that I can lead the manuscript and she can co-lead to help with writing. But now, she wants something out of the project as soon as possible and feels that this manuscript may add on too much workload on me in my final year. And she would like to bring up a discussion with our supervisor that due to timing issues, she wants to lead the manuscript. It's true that she can speed up the processes as I will be busy writing other manuscripts and my thesis. The whole project does need a published paper now so that subsequential works can rely on that. However, I feel a bit uncomfortable about letting someone else lead a manuscript (I will be a coauthor for sure) when I performed most part of the analysis. I don't mind having more workload on my shoulders but I can be slow with many parallel projects. My always states that it's a decision between me and the colleague. So my question is that：
（1）is timing a strong reason to let others take the lead in a manuscript, given that I really want to lead the writing of my own work?
（2）Shall I let my colleague lead the manuscript and take the first author in favor of time? Does the authorship ranking mean a lot? I only had one paper published for now.
(3) If I want to make the conversation, how shall I start?