to original question, for fillet steak
season after, there is no need to season before. and as its fillet, no need to brine.
to take advange of excellent storing properties of sous vide, prep and vac pac steak straight away. then pop into waterbath when ready to cook on Thursday. The steak will be kept from oxidising properties of oxygen, and bacteria will be prevented/ slowed from growth. Just keep in fridge. Not vauum packing will just allow bacteria and pathogens to grow in the mean time, and then you seal them all in before cooking. If you vacuum pack the steak then sous vide, there is no need to allow it to come to room temp. Straight from the fridge to the bath. Feel free to add flavours ( (garlic, herbs etc when vacuum packing) salt is a seasoning not just a flavouring), but not salt in the bag. as a note, fillet steak from fridge would need less than one hour to cook med rare. remember quality of meat is a bigger player than timings. You cant make a silk purse out of a pigs ear!