So...

Click on your profile then Grans_Canary posts. It will tell you that:

You've Started 210 Threads
and Posted 534 Messages

Now look for urls like https colon slash slash www.wrathofthebarclay.co.uk/interactive/board/user_posts.php?start=50&username=Grans_Canary

You need to firkle the 50. The number you want won't be 210 - too small - or 500 - too big, because it displays results in threads and typically you will have posted several messages to any one individual thread.

A bit of messing around led me to User Posted Link which suggests that your first post was May 10, 2005

You can repay me in gin x

May 10 2005

Posted By: Old Man, Feb 23, 23:21:43