Hi ladies, I'm Miranda from thepankou in the links that Linn cited above (thank you so for mentioning my site and visiting!). Everyone has provided such good input so far, and hopefully I can add on what has already been said.
The Chinese label which I am able to read indeed is in traditional Chinese, and it does not in fact say the qipao is from Shanghai. It reads "Guangzhou costume export, Huangsha Taiyun Road". I researched the location of Huangsha and Taiyun Road online, and was able to find some information in a few Chinese websites. It seems that it is part of an area that was very popular for producing Southern Chinese opera costumes in the early 1900s (the most popular area was in fact called Zhuangyuan Fang, but there were a few production facilities also in nearby Taiyun Road), however was shut down largely in 1938 when Japan invaded, and re-established post the Japanese occupation in the late 1940s.
So my estimate is very similar to what others have said above, that the dress is from the latter part of 1930s but prior to 1938. The reason is that the qipao is long (I assume from the pictures, although difficult to know exactly without someone wearing it), and a colour that was very common in that era due to the indanthrene dye (more info in my write up of the era, but basically a very affordable dye that could produce blues and greens). It is in fact true that sequins and zippers were more popular in the 40s, so I don't think we can rule out the possibility of late 40s, but from what I read this particular location was more productive in the 30s, as the re-location back from HK tended to be in Zhuangyuan Fang.
The pen written label of "1924 Shanghai" is almost certainly incorrect that this qipao is definitely not from Shanghai.