There is an interesting reportage in the New York Times by Chandler Burr about a visit he made to the Versailles-based conservatory of perfumes, L'Osmothèque in L'Heir du Temps (some perfume lovers assuredly would prefer to insert the term "pilgrimage" here).
We learn that Jean Kerléo its director was motivated to found it because as a young perfumer he experienced constant frustration over the fact that more senior perfumers would repeatedly tell him that so-and-so accord he had created had been done better or more beautifully in a previous, disappeared perfume (great perfumers are humble).....
There are some glaringly incorrect remarks in the article however. Is it worth mentioning or should we just assume that a journalism article does not have to be completely accurate but offer a good story with easy-to-remember landmarks? Ah well, let's try that once more. Personally I am extremely wary of this anti-intellectual streak. In particular, Burr writes that Le Parfum Idéal (1900) is the first floral bouquet and that before that "perfumers created scents of single flowers." This is a wrong representation that is also propagated by Richard Stamelman by the way.
There was a vogue for soliflores but there had been floral bouquets in the early modern period. The 1000 Flower water (Millefleurs) is a good example. You can read our review of Ess Bouquet (1711) to see an example of a pre-20th century bouquet perfume. Also, it is not a bad idea to recall that Guerlain Jicky created in 1889 included lavender flowers offering the first established pyramidal structure although it seems that perfumers earlier on had already started to take into account different rates of evaporations. If you look at Guerlain's catalogue you can see a perfume called Bouquet de l'Impératrice dating from 1863. The famous Soviet Krasnaya Moskva perfume was called before the Emperatress' Bouquet in 19th century in Russia. Perfumes composed as floral bouquets were abundantly popular long before 1900.
Paul Parquet made use of synthetic materials in a pioneering way for Parfum Idéal, but not necessarily as a first, and L'Idéal is also recorded as being the first one to have been commercialized in a sophisticated comprehensive packaging including a crystal bottle at the 1900 exposition universelle. If it was a first for anything else, it would have to be for something else than being the "first floral bouquet".
On a more practical note, you can hope to find some of the discontinued vintage Patous quoted in the article as they were re-edited at one point as a collection of miniatures called "Ma Collection" and you can even spot full bottles at discounters.
Here's a link to another comment on this article from Octavian at 1000 Fragrances