A few hours later, Shrek overhears the Fairy Godmother telling Harold that Fiona hasn't fallen for Charming, and giving him a love potion for Fiona, which will cause her to fall in love with the first person she kisses.
Shrek overhears the Fairy Godmother telling Harold that Fiona hasn't fallen for Charming, and giving him a love potion for Fiona. This was a few hours later. Fiona will cause her to fall in love with the first person. She kisses the first person.