Strange but meant to be fun question.
I couldn't dress up when I got home today due to visitors calling round, a day when the urge was particularly strong. Three hours later, they left. Although there was some tidying to do, that just had to wait.
I was out of male clothing in less than a minute and fully dressed up a couple of minutes later, bra, panties, slip, dress, suspender / garter belt, wig but not including make-up. Once the stockings were properly hitched up to garter / suspender belt (the fiddly bit at times for me) and heels were on, it was just under seven minutes.
I then tidied up including moving a couple of heavy objects in medium-height heels.
I guess tights or hold-ups would have reduced the time by a couple of minutes, but once I get the stockings hitched up it's worth the extra minute or so as I find stockings more comfortable than either.
What's the quickest anyone else has managed?