Which is the correct preposition?

In sentence number one, either one could be used. In sentence number two, using "on" would imply that the appointment was made on that date, and if the intent is to convey that the appointment is to take place on the 25th, then "for" should be used.

How about "I have a scheduled meeting with your Father for the 25th."?
or "Hey dude, I gotta git with your old man on the 25th"?
or "I have a matter to discuss with your pater later."
Ha, just having fun. I think the first choice is the better one.

William

2. I have made an appointment with your father on/for the 25th.



I don't think so, Setanta. Native speakers are loathe to use the present perfect with a definite past time adverbial. It's possible but not likely, as it's written.

If the intent was to note the date it was made, it would likely be moved closer to 'appointment', as in,

I made an appointment, on the 25th, with your father.

This must be some important papa.

# 1 IS CORRECT use ON