Because you only submitted it 16 hours ago.
You need to be patient - esp as weekends don’t count
Actually impossible to say as there is no guaranteed review time, but your item should be reviewed as soon as possible. You can often refer to the average review times at the link below as a guideline, but these are just averages and the actual review time could be few days shorter or longer than those listed:
what is - esp as weekends don’t count
Reviewers tend not to work on weekends so those don’t count towards wait time