Technically you only need to feed them when the soil is deficient of one or more nutrients. This is probably why you see such a range of advice - people grow them in a range of conditions, composts, etc. For example a pot or re-used compost is more likely to become deficient of nutrients.
Personally I usually only feed them once - usually a few weeks after the seedlings (or store bought plants) have been potted on to their final location. This gives them time to get established. I use a general purpose liquid fertilizer feed. My conditions are: raised beds built up with soil and compost (and annually fortified with new compost), plus pots with mixed store-bought compost.
The only other time I've used a feed was a few years ago when I had some trouble with seedlings getting started. Thinking it was an extreme nutrient deficiency essential at germination, I used the feed as soon as the seedlings appeared. With hindsight I suspect I was seeing damping-off.