Booking a flight

Hi,

“When do you want to fly?”

“I don’t mind. Any time next week.”

Can I say “I don’t care …”? Wouldn’t it be a little rude?

Thanks once more. Ciao

PS: I said “wouldn’t IT…”. Should I have used “that” more properly?

“I don’t mind” is usually the safer choice. “I don’t care” may come across as impolite, abrupt or dimissive, depending on tone of voice and general context.

“Wouldn’t that” seems better here, but “it” is not wrong.