How long does an uncertified channel take to publish?

uncertified channels don't appear in the store and will not be publicly discoverable; you'll need to find the link (default or "vanity") from within your developer channel page and provide it to anyone who will add the channel.
Once you publish an uncertified channel it's generally available "immediately" (within a minute or a few).
Did you actually click "Publish"?  Did you try using the channel code to add the channel to your Roku account?

Is there a way to change what regions it’s available to be viewed in? It still says publishing and when I click the “unpublished” vanity it lets me add my channel and says it’s uncertified and that it will show up on my list of Roku Channels in 24 hours, but the other vanity number when I try to use it, says my channel cannot be viewed in my region?!? :(. All I wanted to do was create a silent story board with words and pictures that my son can watch and the entire channel’s illustrations are about him but I can’t get it to work properly and I feel bad about it :(.

For that matter is there a way to change the channel from private to public?

public requires a certification process, I'm almost certain you don't want that.
Log into Roku site and go to "manage my channels", then "preview and update" the channel you're interested in.  Near the top is a drop down menu that will default to "Preview and Publish" (next to another drop down that says "manage my channels") 
Click on the "Preview and publish" drop down and choose the first option, "Properties", you will see a list of "Channel Stores" where you can click off regions where your channel should be allowed.