with what did he start his theatrical career?
In 1587,  "Chronicles of England, Scotland, and Ireland".
London and theatrical career
It is not known definitively when Shakespeare began writing, but contemporary allusions and records of performances show that several of his plays were on the London stage by 1592. By then, he was sufficiently known in London to be attacked in print by the playwright Robert Greene in his "Groats-Worth of Wit":

... there is an upstart Crow, beautified with our feathers, that with his "Tiger's heart wrapped in a Player's hide", supposes he is as well able to bombast out a blank verse as the best of you: and being an absolute "Johannes factotum", is in his own conceit the only Shake-scene in a country.
how old was william shakespeare when he wrote hamlet Between 1589 and 1613 at the age of 49. who is he? He was an English playwright, poet, and actor. name a few of his poems? "Venus and Adonis", "The Rape of Lucrece", "Metamorphoses", "A Lover's Complaint". what is the third poem about? It is the history of the world from its creation to the deification of Julius Caesar within a loose mythico-historical framework. what are its themes? Mutability, love, violence, artistry, and power are just some of the unifying themes. what is metamorphosis in it? It is the transformation is a unifying theme amongst the episodes. describe the writing style of the author of the poem? It is conventional style extended, sometimes elaborate metaphors and conceits, and the language is often rhetorical in written. did he influence how plays are classified? It is classified as comedies, histories, and tragedies. what was his sexual orientation? Has evidence of heterosexual liaisons, expression of intense friendship rather than romantic love. where was he from? Snitterfield.
UNANSWERABLE "Groats-Worth of Wit" "Richard III" and the three parts of "Henry VI"
William Shakespeare William Shakespeare
London and theatrical career Plays
in print by the playwright Robert Greene in his "Groats-Worth of Wit":
 The first recorded works of Shakespeare are "Richard III" and the three parts of "Henry VI"
wiki:19635390
William Shakespeare [SEP] London and theatrical career
It is not known definitively when Shakespeare began writing, but contemporary allusions and records of performances show that several of his plays were on the London stage by 1592. By then, he was sufficiently known in London to be attacked in print by the playwright Robert Greene in his "Groats-Worth of Wit": ... there is an upstart Crow, beautified with our feathers, that with his "Tiger's heart wrapped in a Player's hide", supposes he is as well able to bombast out a blank verse as the best of you: and being an absolute "Johannes factotum", is in his own conceit the only Shake-scene in a country.