If the port is new and free of scratches then you should be fine.
Clean it with washing up liquid. (Pat the port, don't rub, just incase there's grit on your cloth) rinse with clean water and leave it to dry.
Make sure nothing touches it in the mean time. I have a plastic column that is taller than the port and then put a cloth over the top and secure with elastic band.
Then before going in the water spit and lick the port and let it dry for a minute or so. That should work a treat. If an spots aren't clearing then lick that one bit.
Make sure you don't have anything on your lips like suncream etc and be weary of what you've eaten. Cleaning your teeth before you go surfing helps.