Depends on the setting, characters, etc. One romance novel I quite enjoy,
Mimosa Grove, the main characters barely say a word to each other before they are naked and in bed, but its also because they'd been lovers in their dreams for months. Soon as they saw each other in real life, they didn't really need much in the way of introduction
That said, love itself is generally irrelevant on when they first kiss, depending on the characters (again). Particularly these days, it is not that uncommon at all to kiss on a first date, or more. And, of course, there are occasions where a kiss may come before introductions (maybe at a New Years party, they've been eyeing each other all night, and just before midnight managed to get close enough that they do the kiss thing with each other)
