I think most people try to drop the later feed, in your case the 11pm one, once baby is well esablished on solids.What you could do is adjust the times of the other bottles so that your baby will have last feed at about 7 or 8pm instead of the 6pm one.
I would gradually try to drop the bottle, maybe reduce by oz here and there until your baby is taking enough solids, so you know they wont be hungry.
My daughter is 19 wks and i have started weaning her, so far so good.As it is she doesn't drink much of her 11pm bottle, only few oz, so we are hoping to he her off it completely within a few months.
Just go with the flow, see what babywants..I'm sure it will all fall into place soon enough!
Thanks very much for the information that you have given me, however long it was because the more information given the better. I have certainly taken it into account when I will approach the issue when it comes up