Gucci labels can be a real pain to date and determine value/desirability. I have only seen that label in 70s garments, but I can't tell you how long it was used. Here's a little background on the House of Gucci that may help you understand how difficult dating these items can be.
The G. Gucci stands for Guccio Gucci who founded the company in Florence in 1921 as a luggage and saddlery company. The metal bit motif that is repeated in your outfit was introduced in the early 1950s, so that dates it to at least then. They adopted the GG logo in the late 60s, so if there's any indication of that on the garment then that helps date it as well.
The company quickly expanded during the 50s and 60s with the help of his sons --- Aldo, Ugo, Vasco and Rodolfo, particularly after Guccio passed away in 1953 and left the company in the hands of his boys. It continued to expand and thrive through the 70s.
By the 1980s, business leadership of the company passed on to Rodolfo's son, Maurizio, but most of his cousins have already left by that point. In the late 80s the family sold a 50% share in the company to Investcorp, which proved to be a nearly disasterous move as it began the dark days of the Gucci brand. The brand expanded far too rapidly then, which had a serious adverse effect of the desirability of the brand, product quality and distribution control. Gucci had nearly exhausted its prestigious brand through over-licensing and family squabbling.
During this period, Gucci was mired in tabloid reports spurred on by the insane actions of the family members, crippled by mismanagement and on the verge of bankruptcy. Family members feuded or were thrown in jail for tax evasion. (Later the scandals reached epic proportions with the contract murder of Maurizio, by his ex-wife in 1998.) Some of them created their own Gucci brands --- such as Paolo Gucci --- which makes it difficult to determine what is legitimate Gucci and what was produced under the auspices of someone who could legitimately claim use of the Gucci name but not the brand itself. And of course there were those quality and licensing issues, which make a lot of this stuff far from desirable. Not to mention all the fakes that are out there!
In 1993, Maurizio Gucci sold the remaining 50% of the company to Investcorp, and it was renamed "Gucci Group NV". One of the firm's designers, Tom Ford was appointed Creative Director and assigned the task of bringing the company around. This was largely accomplished with a reigning in of the brand and what most consider the design genius of Ford. Gucci Group was launched as a publicly traded company in 1995, and the rest is luxury chic history.
This is just the condensed version --- in spite of my lengthy answer. There's a lot more to it of course. <i>
House of Gucci: A Sensational Story of Murder, Madness, Glamour, and Greed
</i> by Sara Gay Forden is a rather interesting read.
