Dr. Drake’s dates are much too recent.
You need to come up with a chronology that fits the whole I-E tree. Italo-Celtic certainly separated from Balto-Slavic and Indo-Iranian well before those latter two separated from each other, so if Italo-Celtic split off 2000 BC, when did Balto-Slavic and Indo-Iranian separate from each other? Indo-Iranian unity is usually estimated as at least several centuries. When did Indo-Aryan and Iranian split in Dr. Drake’s model? Well after Sanskrit is attested, it would seem. 
I think Ringe’s team is about as credible as any. On page 29 of this slide-show Italo-Celtic is shown splitting off at 3200 BC; Italic and Celtic separate from each other about 2600 BC.
There is much uncertainty of course and Ringe himself (who focuses on linguistic evidence rather than archaeological clues) avoids dating altogether. However I think the path lengths in the diagrams (pages 2, 39) of the link are intended as proportional to quantitative linguistic change.
Are Ringe’s team and I wrong? Dr. Drake, can you cite a credible historical linguist advocating dates anywhere near yours?