Hi and welcome!
There is no strict rule about when you start shush pat really. If u find that standing up and shush pat works better for your LO then do that. She is so little still and it will take time for her to het used to shush pat, in fact a lot of babies cry before sleep, it is normal.
When my LO is cranky is still have to do shush pat whilst walking around to calm him, he will calm down after a bit of crying, but it did take time to get here. If he isnt cranky or tired i dont need to do shush pat at all, only a bit of humming whilst walking around, in fact he just doesnt like it when i sit down still, so to assure you, you aren't doing anything wrong and do the wind down that works for you and your little one, the idea after all is to set the stage for sleep and if shush pat relaxes her and calms her, thats great.