You choose whether to make a copy as the demonstrate ability resolves. This happens before the original spell resolves. Your copy goes on the stack above the original spell.

If you copy a spell with demonstrate, you then immediately choose an opponent. If they copy the spell, it goes on top of the stack.

If the spell requires targets, you choose the target of the original spell as you cast it. If you create a copy of the spell, you may choose new targets for the copy as you create that copy. Similarly, the opponent you chose to create a copy may choose new targets for that copy as it's created. In other words, your opponent will know the targets of your original spell and your copy when choosing the new targets, if any, for their copy.

This means that if you cast a spell with demonstrate and both you and an opponent copy it, the opponent's copy will resolve first, then your copy will resolve, and finally the original spell will resolve.

If you cast the spell and choose not to copy it, no opponent will get to copy it either.

If the spell with demonstrate had any modes chosen for it as it was cast, the copies will have the same modes chosen for it.

If the spell had an X value chosen for it as it was cast, the copies will have the same value of X.

If any additional or alternative costs were paid to cast the spell with demonstrate, the copies will see those choices as well. For example, if the spell has a kicker ability and was kicked, the copies will also be kicked.

Unlike other creature types in Magic that are each only one word, the two words "Time Lord" represent a single creature subtype. Time Lord is the only two-word creature type.

Neither "Time" nor "Lord" are creature types. Some older cards were printed with the subtype "Lord," but all of those cards have updated Oracle card text that removed that type.

If an effect instructs you to choose a creature type, you may choose Time Lord.