Use dans to talk about an amount of time.
L’avion part dans une heure.
The plane leaves in one hour.
Nous partons à Montréal dans deux semaines.
We are leaving for Montreal in two weeks.
Be sure to add à after penser to mean to think about.
Nous pensons à cette chanson.
We are thinking about this song.
And notice that words like souvent and beaucoup come between penser and à!
Je pense souvent à mes grands‑parents.
I often think about my grandparents.
Il pense beaucoup à ses vacances.
He thinks about his vacation a lot.