Czechoslovakia was formed at the end of WWI and officially proclaimed a nation on October 28, 1918. Use of the name on glass likely started in early 1919, at least that would be my assumption. I doubt it started immediately.....
The only other real spelling that is seen, that I am aware of, is the French version of the country name. There are variations of the name which are hyphenated or not , and generally hyphenated examples be used (quite loosely) to date production to the 20's.
It is my understanding that the use of the hyphenated country name was uncommon by the very late 20's..... but this is not written in stone and should not be used as a formal dating method...... As an example, I believe the Loetz oval, which is hyphenated, was used well into the 30's.....
Hope this helps, Craig