On Seed&Spark, your campaign is successful (meaning you will receive the funds raised) when you reach 80% of your goal. We call this "getting the Green Light". You can get the Green Light at any point while your campaign is live. Once you've received the Green Light, you can keep raising funds until your campaign ends, even past 100%.
If your campaign receives the Green Light, it must still run for the full amount of time of your campaign period. It cannot be ended earlier than expected due to a Green Light.