Just a thought, Barbie 400 ....
I appreciate that you wish to prepare - but without the foreknowledge of the exact position of your stoma - you might find that what you buy, certainly pant/brief wise - may not be the 'appropriate cut' [viz high leg bikini brief mini brief g-string etc] .... so do not overbuy as you may be 'unfortunately pre-prepped'
One thing to think about too is the cut can be more comfortable with a brief which is clear of your stoma [allowing for the pant line not to rub inappropriately across your stoma - particularly immediately post-op] ..... But if you are at the point of having discussed such detail [usually there are options for placement - but no guarantee as surgical placement may need to vary despite one's first 2nd third choices] - depending on your surgeons' skill and the procedure in theatre and what is found / happens during surgery .... then I guess you are better placed to commit to more shopping.
Trying stuff on is pretty important too - [I realize I'm stating the obvious] for I find that sizing on mail / e-commerce order - even taking into account online reviews - does not necessarily match the detail of what arrives - comfort can only be checked once a product is worn [so I get your wish to get some groundwork done :-))
May I respectfully suggest, you do not predetermine a 'mind-set' before the surgery is done ..... just to prepare for flexibility - GOOD LUCK - and please do not be deterred by my words - but just be aware so you are not 'wrong-footed' or disappointed or wind-up with a surprise variation of exact stoma position ..... for believe me the position of a top [cross line] of mini brief and a bikini brief coupled with the leg edge [and the size chosen within a range once sourced] can be crucial to one's comfort and your own good tolerance / happiness :-)) [I speak of UK market ladies and girls underwear - the US retail may be different] - but probably not. [Our stomas are particularly sensitive to a pant line or jean belt etc when coinciding right across the middle of it - BUT JUST CLEAR OF IT CAN ACTUALLY BE AMAZINGLY COMFY] and there is something 'very very normal' when first getting your own underwear on ... helps one to feel feminine again!
Hope thoughts don't sideline - for only trying to broaden understanding here .... for personally [I was very small waisted when my surgery was first done [18 inch waist] and I found that off the shelf [rather than ostomate specific clothing] suited my wish to have as normal a body image as possible .... and couple that with a non-medical appliance looking bags - is a big confidence booster - for 'body beautiful' is a healthy self-image to protect and maintain, [and mentally disregard the early wound appearance - for that quickly fades] so don't be too needy of 'covering up' ..... because being as YOU as possible - as early as possible, rather than feel one is needing to change one's 'personal image' where a medical appliance either dominates or needs to be 'covered up' is a really healthy aim and positive image to hold .... Just shared food for thought .... it may help.
BW
~ ~ ~ ~ ~ Jayne ~ ~ ~ ~ ~