I'll speak from my experience here... but it's not something I would use for every situation.
B's parents live about 1500kms from us, his brother lives 1000kms. We go down there once a year, and USUALLY at his brothers place we get seperate bedrooms (we always do at his parents - even though they usually can't understand it, as B has up until now always shared a room with his gf when visiting his parents).
Last time we went down to his brothers, we had to share the futon in the lounge (the lounge was SO tiny, it took up the entire room!), as it was a one bedroom. We slept in it for 10 days all up - and NOTHING happened.
Same with the trip back home - we had to stay somewhere overnight, again a double bed, and again NOTHING happened.
I guess we had the value of hindsight though. We had both been involved in sexual situations before, and knew how much it had messed up the relationships we were in at that point, so our determination NOT to do anything, no matter the living/sleeping arrangement, is pretty strong.
I don't think everyone is like us, and I don't think our situation SHOULD be used as a reason as to why it is okay to do it - but from someone who has been there I personally know it IS possible to sleep regularly in the same bed, and NOT do anything.
It has to be your own personal determinations though - and you have to remain steadfast to the ultimate goal. Work out what that goal is - and then act accordingly.
Nothing anyone tells you on here to do/not do is going to help - this is a decision you two have to make all on your own.
Whether that means you don't go on a holiday on your own until your honeymoon - then so be it. If that means no sleeping in the same bed until the wedding night - so be it. The point is YOU have to be the ones to make the decision - and then YOU are the ones accountable to that decision, and whether you stick by it or not.
We stuck to ours, and never once slipped up - and I have no regrets.
Sasch
ps. And it's pretty easy to stay fully clothed when sharing a bed/room with your bf/FH - you just use the bathroom to change, and ensure you wear a pyjama set to bed (not a nightie - as they have a tendency to ride up)! That's what we both did anyway!