Should I try and get him to vomit?

Yes... Syringe him 3% hydrogen peroxide

The dosage is 5mL/10 lbs (1 teaspoon for 10 lbs)... The dog should vomit within 15-20 minutes..

If your dog does not vomit, you're going to have to take the puppy in to the Vet Monday. Tinsel can cause a huge problem if the dog ate enough of it.

Linear foreign bodies can be very serious and should not be taken lightly.
While Hydrogen Peroxide is a good method of making them vomit, the window of opportunity has long passed, since the tinsel is now making it's way down the small and large intestines. I would strongly suggest a Vet visit first thing Monday. Stringy things can cause the digestive tract to "bunch up" and may even have to be removed surgically.
On the other hand I've seen many weird things pass all the way through a dog, I am definitely not saying I always trust that.
Just an end note-If you see the tinsel making it's exit it is best to not pull it.

You should take him to a vet if he seems a bit off or is acting a bit strange.

Lady Sam is 100% right on.

But even a single strand of tinsel, string, thread,long hair, or even a broken rubber band, can cause the intestine to 'bunch up' on the object, similar to the wrapper on a straw if you tear off one end and push it down to the other end. That is how the gut acts when one end of the object becomes tangled in the fine hair-like surface of the cells lining the gut. Peristalsis pulls the gut together. Something like thread can actually cut through the wall of the gut. Keep an eye on the BMs in hopes of finding the problem stuff.