This cron executes the command every minut of every hour of every day in every january month.
You have to specify one minut exactly, for example:
30 0 1 1 * ...
00:30 On 1st January, every year.
The top line of the script must be the path to your php binary, I guess its correct your path. Don't forget to give execution permissions to your script (chmod +x script.php)
I hope this can help you.