The inlet should just start to open as the piston just hits Bottom Dead Center (BDC) so that steam admission begins when the piston is just ready to start ascending the cylinder.
Solder is the preferred method to attach the inlet pipe to the steam admission valve body, but now that you have used a "glue" those surfaces will have to be super well cleaned before solder will take. Of course, with soldering, you can mess up and plug the inlet as well, so proper care and technique are needed!