If an artifact or land that becomes a creature this way has been on the battlefield since the beginning of your upkeep (even if it wasn't a creature at the time), it can attack during your turn and its abilities may be activated.

Tawnos's Tinkering doesn't grant haste, so if a noncreature permanent that entered the battlefield since the beginning of your upkeep becomes a creature this way, it can't attack until your next turn. Any activated abilities that it has with a {T} symbol in their cost also can't be activated until your next upkeep step. Notably, this means a land that entered the battlefield after your last upkeep can't be tapped for mana if it becomes a creature this way.