Help with neutering and training new rabbit

Hello, I used to be on this forum when I was younger and trained my rabbit for jumping. I used to have 6 that lived outdoors. It's been a few years now and I've recently just got a new rabbit who I am keeping as an indoor bunny. I've had him for about a week now and he is 1 year old halequin dwarf lop sized and called him Bojangles! I rehomed him after his previous owners couldn't look after him no more so he's about a year and a half old. From what I've been told by them he was used to breed from however I've got him booked in to be neutered on the 31st March (8 days) I've need a little help with litter training him, any ideas a ect?? As he is getting a little bit too brave and is wee'ing and leaving dropping everywhere!
Thanks

Has he got a nice biggish litter tray filled with hay as this helps to litter train sometimes! Good luck.