I use Drop Box.
I copy the file into a folder in Drop Box on the computer. (Takes a short time for the file to upload to the cloud. you can watch the indicators on your task bar to see when it is complete.)
Then open the Drop Box app on the iPad and use "open with" to open the file with FileMaker GO. this both copies the file over to the FM GO location and also opens it.
You can send files back to Drop Box from FM GO to copy them to your computer as well.