With a study of J. Brychta, M.B. Volf - Živé sklo on Jindrich's site I have gone a bit further using image A.
There is a clear evolution in the development of Brychta's figures and based on that evolution the pieces shown in image A are very unlikely to have been made before 1927 and after 1930, with the greatest likelihood that it dates to 1929. I still lack the crucial evidence of when he became director of the shool and this may well be contained in the Czech text... so hopefully a reader of the language coud see if it is mentioned.
It is however fascinating that he evolves to pure lampwork forms and at this point no longer considers them original in method but that the discipline and flexibility of working with the wire based forms, which appear to have evolved from the humble necklace, had lead to greater expressiveness and use of lampwork as an artform. It could certainly be said that the forms he created through the 30s represent a true artistic renaissance in lampwork art. Yet this in turn evolved into the very rigid lumpy ZBS figures that most are familiar with today and have lasted some 70+ years in production. What the three pieces in A. also show is possibly the critical turning point. 'Pippi' on the right has hung on to the old wire strung approach yet the rest of her has developed one stage further. The rope trick artiste, or necklace salesman?, appears to have a spread of rope or bead necklaces in front of him and is mounted on a powerful base, possible a jewellery box or simply a bold statement. Finally at the left, while still clearly in the same stage of development technically as the other two this religious figure does somehow fit with the 'moderne' ZBS style that really started to emerge in 1937.
1929 is a comfortable date for me on this folder of material but I am still open to input and other ideas.
Finally what of C. ? There is just enough information in the image to tell that this piece is cut glass. Surely created at some point after Paris 1925 when the Art Deco design concept kicked the butt of complacent glass design across Europe. It is such a iconic piece that some most have come across this before... who would be the contenders for making this in the late 1920s?