Firstly, is he starts to fight going into the bed, don't force him, as he will only hate it more kwim? I have heard of people using travel cots to make do in the mean time.

Try to make it fun for him, take him shopping for linen and let him pick his favourite characters out and make if fun when it comes time to make up his bed.

Start a special routine for his 'big bed' like special stories etc.

Also, when my three started in a big bed, we didn't have rails, but I tucked a pillow under the edge of the matress to stop them rolling out, because they had to roll uphill kwim?

Good luck with it Christie, and I'm sure he will be fine with it.