What’s a reasonable time table for planning a international trip?

[Anonymous]

So I got into an argument with my mom about buying tickets for her and my niece to London as a surprise birthday gift for my niece. Problem is she wants to leave next weekend and stay for a week & tickets for both of them together are close to $4000. I told her that international trip should’ve been planned out at least 3 months in advance to avoid high prices but she said it wouldn’t have mattered. And to make matters worse, my niece’s mom just applied for a expedited passport yesterday hoping it’ll be here before next week Saturday. Am I right that all this should’ve been planned out months ago or trying to do it last minute is ok?

[MTC29]

Tickets for international travel should be purchased no fewer than two months ahead of the planned departure date. Three or four months would be better.

[Guy13]

6 months without passport.

[Guy13]

Tickets are usually cheaper 5 months out…

[FilmGuy93]

A couple months would probably be best