Hi. I really want to save this quest line for last on my evil character, but if you can become a Vamp Lord very early in the quest line I am going to install the DLC, vampire attacks be damned. I have not installed it because of the attacks, but I think I am ready. I want the new Falmer armor, the crossbows, and the dragon weapons too! So how early can I become one? Thanks in advanced dudes.

I think its at the end of the second quest.. so, around 30 minutes into the questline

Yeah, pretty early. You technically have to join the Dawnguard first, and then they send you to investigate a cave, once you're done there you head straight to the vampire castle where the option is presented to you.