Yes, that is normal. Especially for a toy breed, you may expect the pup to be able to hold it for as many hours as her age in months. 8 weeks=2 months=2 hours. I would be using a pen too, as Susan suggested. Choose an elimination spot that works for you: disposable pee pads, washable pee pads, litter box, Piddle Place, etc.
First time Chihuahua owner with many years of dog experience!