This form seems to be very common in modern conversational Russian, e.g.
Давайте-ка не будем пороть горячку.
This form also has its more colloquial (and dialectal) counterpart with -ко:
Слышь-ко, чё скажу...
All in all, the -ка imperative (particle) is attested as early as in Lermontov's Borodino:
Скажи-ка, дядя, ведь недаром...
But what is the eldest attribution of this form together with its geographical area of usage?