When I enterred shidduchim, I had an older sister who was still single. At the time, she was adamant that I had to wait for her. A prominent Rav told my parents that if a really good name came up for me he would speak to her and help her change her mind. Before that ever became an issue, my sister told my mother that she is ok with me going ahead of her. Both of us are still single, so nothing came of it, but I still think of that as an enormously mature and impressive gesture on her part.
That being said, I am pretty sure that it isn’t really up to us in the end. Hashem will decide when the right time for me and for my sister is, and we can only daven.