When did Jake and Paige's relationship move from just being friends?

When Paige turns seventeen, things begin to change between her and Jake. On the night of her junior prom, Paige is at Jake's house, since she does not have a date to the dance. Jake does not know it's her prom night and he already has a date. Jake asks Paige to help him get ready for the date. Paige grows upset and runs out the door. Jake comes to Paige's house after he realizes why she is so upset. Jake admonishes her for not telling him about the dance and then he kisses her.