Kedarnath will be opened after April month. you can visit Tungnath and Kedarnath after April. But if you want to go for a winter trek, this is the perfect time for Tungnath and Chandrashilla. :)
I think May will be the best month to do both treks as kedarnath temple will be open around mid-may this year.you can also go in October to mid-nov as well. pls let me know if you're interested to go around end of may.