I teach K-4. I only see kids 35 times so plan to do a 5week code unit. Should I use course a-e or the two express. Any ideas best to implement

I only will be doing a 5week code unit so should I have the students use the a-e course and they do what they can then next year just promote them all to the next letter or should I be using the express k-1 and the express for 2-4. Does anyone have the any thoughts on the best way to implement.
Thank you