I think they both would have been 2 when we moved each of them and both were in the cot for a bit with the side off, and then into a single bed. DD was easier, she happily went straight in. DS was a bit trickier. He took weeks to convince to move rooms, so I'm glad I started early as we needed the cot for DD!
Not sure how old your little one is, but they do adapt pretty quick - though it did take months and months to stop kicking their blankets off. I eventually turned their blankets around to tuck the length in on the sides to keep them warm in winter! Still do it now with DD and