When do you get the alohomora quest

[Nightshade]

I've progressed with the main quest to a point where I need to get through a locked door, but I dont have alohamora.

[Denniss]

side quest with Mr Moon to collect the statuettes at night

[Akela]

Questlevel 14, I did nearly every sidequest, I am currently lvl 25 and do now this main Quest to get the skill.