Getting To Know Shakespeare Webinar

Thank you for the mini-seminars on Shakespeare.  Could someone explain to me the reason for the 1850 begin- date for doubting the authorship of Stratford Will?  I was under the impression that there was a controversy as soon as Venus and Adonis came out in print. (1593) Gabriel Harvey made reference to “that fair body of the sweetest Venus in print [V&A] as it is redoubtably armed with the complete harness of the bravest Minerva” (Minerva/Athena known to Elizabethans as the Spear Shaker). Harvey had previously referred to Edward de Vere, 17th Earl of Oxford as a spear shaker, in 1579, when he encouraged him to lead in military thought, not letters.  Then (1597) John Marston traded remarks with Joseph Hall, Marston saying that “Labeo” (i.e., a Roman who hid his work behind another name) was writing erotic poetry. [Venus and Adonis being considered erotic] Was Shakespeare hiding behind another name? Or who?  Marston guessed Bacon was the writer hiding.  This appears to be a much earlier controversy about the identity of Shakespeare the writer of Venus and Adonis than 1850.  I wonder if someone would address this contradiction.