Don’t wait for help
Find something to collect the incoming water. A Pan, bucket or trashcan will work. Remember to empty them periodically.
Remove damagable items
When possible remove items such as papers, computers, furniture etc. from the area. Large items that cannot be moved should be covered in plastic. A plastic trash bag cut open or even a shower curtain will work.
Stop your Ceiling from Bubbling
If you notice your ceiling starting to bubble, take a sharp item (a screwdriver or even a pencil will work) and poke a hole into it to release the water, this will prevent the ceiling from becoming worse or even falling.