RP07: invitation wordings help please

For wedding date on invitation, do I have to write the date on words?

example:
My wedding date is Nov, 16, 2007 at 6:30pm
Do I have to write:

The Sixteen of November
Two thousand and seven
at
half past six

is there any rule?

It's a formality thing more than anything else. You can write it however you want to. Most people just write the X day of X month X year at X time because it looks more formal, but if you want to write it out June X 2007 at X:30, then you can do that too.

Mine read
On the 14th Day of October Two Thousand and Six at One o'clock in the afternoon

(or something VERY similar to that)

Mine were like this:

On the seventh day of July
Two Thousand and Seven

at 4 o'clock in the afternoon.

hth