Sister,

I have two thoughts. First, the posture of the lay faithful in the EF is regulated by custom, not rubric, so not knowing perfectly when to do these things becomes an opportunity to learn more deeply about our liturgical culture and the faith itself. Second, I'm attaching the text of a conference I gave some years ago, about how to not feel like a foreigner in the TLM.

One comment I'd like to make: observing customs are a great opportunity for charity. There are some who follow the directions of the "Red Missal", there are others who (gasp) follow Dom Daniel Oppenheimer's instructions. No two parish is completely alike. So yes - follow the directions of the Red Book by all means if you need something to set a standard. But if you see someone else following the 'Continental customs' or whatever, remember that they are not ipso facto heretics.

This may be helpful to some: when I was tasked with providing the music for my first solemn TLM, I had no idea what to do when. My priest helped me devise this choreography guide. This isn't the same as a sit/stand guide, and a few things may be different in your circumstances (like whether or not to play over the final gospel and whether or not the choir should descend for communion or wait to receive until the end) but this is how I was instructed to go about it from the west end. I've used this choreography guide 2-3 times now, and it has always been a tremendous help, and my choir is always happy to have it as well.