Pretty sure the wait time is in ms!
When you do any command with wait, I do believe that you wont be able to perform any other commands inbetween that wait. Meaning if you theoretically put a vstr that has a wait of say 5 minutes, and its running -- then the server wont accept any rcon commands (and maybe even admin commands) for 5 minutes until said vstr finishes. Using VSTR to do super long "waits" is probably not a good idea and not just for this reason, but I do believe it takes a toll on the server performance too. Dont quote me on all of this but it is what I have been led to believe based on experience although I have not actually investigated it thoroughly.
What you rather want is something that externally writes svsay after a given time. With Linux, you would have to use crontab to schedule it. But that is slightly bit more complicated than using JKA commands obviously.
So the easy alternative is to simply do message at the start of every map (in a vstr that lods the map, add a short wait time and drop the message you want there). But doing it for several minutes or hours is where I think you probably should reconsider. Once again not sure but I think thats the case.
Try bringing up the console and connect doing /connect 127.0.0.1:21000 or /connect 127.0.0.1:29070. Make sure your server is up on the CP or whatever you are using.
If that works, then its likely that your internet connection doesnt have open ports for JA/your NAT settings are restricted or there is some firewall preventing it from being publically hosted.
If that doesnt work, then your server isnt launching properly and we would probably need to see what your CP is saying to troubleshoot it. Preferably with /developer 1 or /developer 2 enabled on the server.