Christmas and the end of the autumn term was more than likely an extra stressful time for the child or children with autism in your class. As I wrote in this article, there would have been lots of extra changes and sensory overload as well as unpredictable events. Some children with autism do like Christmas and I hope that all of them had a good holiday at home, but it's likely for some that it was just as stressful, and for many of the same reasons.
A new term is a good opportunity for you to look afresh at your pupils and review where they are up to after their first term in your class. I don't mean by looking at their academic data (as I'm sure that this will be a feature of your planning this term) but by putting that aside and looking at the whole child you may find some helpful insights to enable you to make the rest of the school year successful for them.