There have been instances where a lady completely rocks me from head to foot. Some worked out, but most did not. But, some will argue that love requires a more in-depth feeling, which can only be obtained by engaging the person for an unspecified period of time. I think love is an evolutionary process, that morphs as time passes and the relationship broadens. So, I do believe that a person can develop an immediate first-phase love. However, it may never proceed beyond that point.
For example, you could have the most beautiful, vivacious lady appear and leave you in a state of total bewilderment. Then she takes her coat off and her tee-shirt reads, "I Luv Gee-Dub". Poof, the moment is lost.