Seasonal Events vs. Search Engines
Search engine time-lag
At particular times of the year, lots of churches make a special effort to invite local people to come to church services. For example, there may be an outsider-friendly Christmas carol service, an evangelistic presentation of the Easter story, or even an 'alternative' Halloween. Naturally, it is desirable to advertise these events on the church website so that they will be found by someone searching for, say, "Christmas services in Vestal".
So far, so good. But search engine time-lag creates a problem for the unsuspecting church webmaster. By the time your church minister tells you what the Christmas services are going to be, it will probably already be November. Suppose you manage to get the details onto the website by the 1st of December, and submit the relevant page to the major search engines. You could find that it takes around two months before the page is indexed by the search engines. So someone searching for Christmas services may not find them until February!
Solving the problem
Careful website design can reduce this problem significantly. Note that wherever possible, menu items or information sections of your site should be in a sub-directory, rather than in a specific file (although a specific file can also work, but is far more limited) - that way you can change whole sections of content without having to change links or addresses.
The solution is to work out which special events happen every year (e.g. Christmas, Easter, children's summer holiday club, etc.) and then create a page (or directory of pages, where possible to group logical things together) for each of those events. By building and organizing your site in this fashion, search engines will be able to build link indexes of your site NOW, and the content itself can be changed when appropriate.
Key note: Realize that search engines DO NOT scan all files and directories found on your server, but rather visit your site as if they were a visitor, logically following all the links that it can find on your site.
Of course, you probably don't yet have most of the information you need for these pages. But it is still easy to write something based on what happened last year, and you can always go back and fill in the details nearer to the time. For example on a Christmas page you could write:
Each Christmas we have a number of special services to celebrate the birth of Jesus. You would be very welcome to come to our traditional Carol service, or if you have children they may enjoy our fun Nativity service. For further details please visit this page again nearer to the time, or contact us.And for placement, (let's say that my church site is "mywonderfulchurch.com"), I would build a section of my website in a "christmas" sub-directory:
http://www.mywonderfulchurch.com/christmas/And then link to that, rather than to any specific (or dated) file/location. This way, the content of the page is relavant, and the link to the information does not change (so search engines can list it, and people will always find relavant information at this address).
If you can include comments from people about how much they enjoyed the event last year, or photos, then so much the better.
Remember that you need to create a link from the rest of your website to each of the pages you have written, otherwise they won't be indexed by the search engines. The easiest way to do this is to have a "diary" or "what's on" page, and then list them as "forthcoming events".

Do not define yourself by what you are NOT, but by what you ARE
