No requirement for dates. We submitted about 50 pictures but our adviser said that was more than enough. One of the things that was stressed to me was to try and ensure that the pictures don't look like they were taken on the same day, in other words pick ones out with a variety of scenery and in a variety of clothing.
My wife and I had only known each other for 6 months prior to the application. And we were successful. Things like hotel receipts, ticket stubbs, etc anything that proves your fiancee was in the Philippines and of course chat logs emails and itemised phone bills.We submitted quite a number of relevant receipts that I had collected during my visits to the Philippines. And your fiancees passport stamp for entry into the Philippines.
