Is it a red flag if someone starts talking about the future too early in the relationship, and how should you handle it?

Does silence often prepare the ground for a true, deep dialogue between two people that can't listen to each other?
I’ve been really frustrated lately and I was finally starting to get better then my doctor told me he needs to wait to send one of my meds until I calm down and it’s agitating. How do I tell people I’m not in the mood to talk without being rude?