Small Steps:
If you have access to a chair, just sit in such a way that your back is not resting on it. Much easier on your knees. Liberation doesn't depend on you sitting seiza or cross legged or in lotus position

Practice sitting on a chair now, before you leave for the center.
Also, I would start on the
anapanasati in earnest now, and continue on with the prescription at the center. Personally, I would enjoy having that momentum going into the retreat.
Finally, per Stuie's recommendation, I also endorse cultivating a sense of ease. Don't worry so much about stream entry, but focus on the opportunity at hand. A little gratitude can also allow some nice heartfelt qualities to arise.
Haha this is my struggle small steps. If I sit in a chair without my back resting on it then I have to use energy to keep my back straight. It is not nearly as effortless as when I am sitting on a stool. This is why I prefer the stool, if I can work out its kinks that is. The effortlessness needed to maintain perfect posture allows me to get deeper into the meditation.
Good idea on the anapana too.
matthew sexton:
Last time for me, in your same situation, I wanted to talk to the assistant teacher about SE. He said something like: "come to more retreats, we will teach you about the ten paramis, that will lead you to stream entry". I found that kinda annoying.

The pagoda (are you going to Kaufman TX?) is such an echo chamber, especially compared to my basement, I ended up wishing I simply stayed on my pace at home instead of the travel and disruption of the retreat.
Matt
It's funny you mention that Matt because I has some similar encounters with the assistant teacher and other retreat assistants last time. They seem to turn off when you mention things like this and instead give Goenka-esqe advice. Nothing wrong with that but it's not what I was looking for. I am attending the center in Shelburne Falls, MA. They have an amazing facility set up there and delicious food. These cells are sound proof! It's the perfect environment if you don't freak out.
Pål:
I mean arching the lower back so that the butt points more upwards and you have less of it's space on the cushion compared to the tighs. That doesn't mean the cushion should be more forwards. Hope this makes sense. The back tends to loose the arch after a while, then you can just re-establish it. With practice the arch and glute positioning can be held without effort for longer periods of time. But I realize you don't have much time before the retreat and you should go for the posture most straight and effortless imo.
take this with a grain of salt since I'm not into nana cycling as you know, but: I agree with Small Steps about starting anapana right away! And don't forget to relax, especially the face, while doing it. You could also do noting with the nose rather than the abdomen as a focal point, that way you'll practice both Goenka style anapana and noting.
I have a hard time picturing what you are talking about, sorry Pal. After this retreat I might mess around with more postures but sitting seiza on an elevated stool is the most effortless posture for me if I can get the knee crushing pain fixed.
Nick N.:
You'll do what you want, but one of the central rules of the retreat is that you don't practice other techniques.
I know. I respect their rules and what they are doing and I am following them otherwise, but this time around I need to bend a few of them in favor of my goals. Luckily the rules I am choosing to bend will not disrupt anyone else but me. I am hoping the choices I make do not cloud my mind with regret and things like that.