Will be in Amsterdam the 1st week of May. We would like to visit the factory and would love input on transportation from Amsterdam to the factory. Thanks
Take the train from Centraal Station. You can buy the tickets the same day. You can then take a nice canal boat ride to the factory.
Use the train planner of the Dutch Railways for getting from Amsterdam to Delft.
The website of the Royal Delft factory gives you information on how to reach it from Delft station, including a link for the boat trip.
If the boat doesn't fit your schedule, you can take a bus from the station to a stop near the factory. I've done it, and it's a five-minute walk from the bus stop to the sight. Ask the bus driver where to get off.