Before he even reached his true potential and transitioned into The Merlin, Tim spawned a thousand different universes as a subconscious afterthought:
http://i.imgur.com/CIFmqM5.jpg
http://i.imgur.com/N7ujMkE.jpg
(as the second scan states: he also sent a sliver of himself to each one.)
*And to be clear: in The Books of Magic, 'world' is typically used interchangeably with 'universe', 'realm', 'dimension', and 'reality':
http://i.imgur.com/YyWkW5j.jpg
Additional confirmation of this can be found at the end of the same series, when Tim and the Faerie Queene once again reiterate that entire universes(not just worlds) were at stake:
http://i.imgur.com/fjgVwl6.jpg
A much weaker fraction of Tim's totality destroys one of his realities:
http://i.imgur.com/qn1dguy.jpg
(this scan also confirms that all of Tim's creations were undoubtedly full-fledged universes.)
Further proof that Tim can easily obliterate dimensions/universes:
http://i.imgur.com/iin3UWR.jpg
A future version of Tim is shown killing Spectre, along with every mage on earth:
http://i.imgur.com/yoYK9Uh.jpg
http://i.imgur.com/d0mOcuS.jpg
"That's you, Tim... You as you are now [...] I'm sorry, kid. It already happened."
...And as The Merlin, Tim bonded with the 'Song of Creation', which endlessly makes and remakes existence:
http://i.imgur.com/rlGZ31e.jpg
