If you commit venial sin, simply confess your sin to God in prayer and say the Act of Contrition.
If you commit a mortal sin, go to confession at the next opportunity. Look up the confession schedules for all the churches nearby and go to the next available one. I don’t think it would ever be necessary to ask a priest to hear your confession the next time you see one. You still can, I just don’t think it’s necessary.
You are not required to confess venial sins. Any act of contrition and other prayers removes them, as do acts of mercy, the Confiteor at Mass, and receiving Communion.
An act of perfect contrition (the primary motivation being sorrow for offending God) is made with the firm intention to get to Confession as soon as possible. That is a condition. If you make such an act with that firm intention then if you died before getting to Confession your mortal sins would be forgiven. However, assuming you don’t die you cannot receive Communion prior to going to Confession, unless there was some grave reason to do so.
An act of imperfect contrition (the primary motivation being fear of Hell) does not forgive mortal sins and Confession is a must.