Hi MNSandy,
Welcome to 5 Star! I've seen you often at another forum. Glad to have you join us over here!
Not sure, but I think you mean DATA feeds, not RSS feeds???
(I changed the subject of your post to Datafeeds)
RSS feeds are generated automatically from blogs,
datafeeds are merchant product feeds.
Typically if you have lots of different products you should offer a feed right away. There would be no reason to wait. Ideally if you sell more than 10 or so products, offering a feed would be beneficial.
Be sure your feed is set up with good and correct categories and sub categories if applicable, both long and short description so affiliates can choose the option that fits their site best is also a good option.
Here's an article I wrote way back in 2003 for WebProNews.
Double Affiliate Conversion Rates with a Datafeed
Hope this helps.