for visiting suppliers/factories, some of the customers might think that interpreter just need to interpret what they say to the other party so that not giving schedule or rough idea for interpreter to prepare. I strongly suggest you to send your schedule or meeting details and visiting address and their contact details in advance for reasons as below:

1. interpreter can prepare necessary terms or paper materials for your meeting in advance which makes your communication easier.
2. interpreter normally will contact suppliers/another party to double confirm about time and address to arrange meetings as per geographical locations to save time and energy.
3. base on locations, interpreter will advise to rent car or go by taxi or metro.
4. some clients might need interpreter to help to find suppliers for them which takes times. giving details in advance will help interpreter to search useful information or even get quotations for you before visiting so you can compare and select your favorite one.
5. there might be some unexpected situation which needs the interpreter to reschedule your trip.

hope you enjoy your trip in China.