You should wet a coffee filter before using it as wetting the coffee filter before using it allows for and ensures a more even extraction of the coffee flavors and prevents papery flavors from the coffee filter.
Wetting the coffee filter before use also leads to a cleaner and more consistent cup of coffee by allowing the water to saturate the coffee grounds evenly instead of them being absorbed by a dry filter initially.
You can leave coffee in the filter overnight so that it's ready to be brewed the next morning.
You can put coffee in the filter the night before so it will be ready to brew the next day.
Some coffee makers have a setting and timer to automatically brew coffee in the morning and if your coffee maker does you can add the coffee grounds to the filter the night before and add water to the reservoir the night before and set the time for when you want the coffee to brew.
When the time comes the next day then the coffee maker will automatically turn on and start brewing coffee.
You can also add coffee grounds to the filter the night before and add water in a regular coffee maker and then when you get up in the morning you can turn the coffee maker on to make the coffee.
I do this myself so that the coffee will be ready quicker before I have to go to work.
After I get up in the morning I go start the coffee and then go take my shower and by the time my shower is done and I'm dressed for the day the coffee is ready.
It saves me time by already having the coffee in the machine and ready to brew.