It is too early to know for sure which weekends they will do them for sure - all we can do is look at the weekends they have been organized in the past and from that more or less estimate when it will be held in 2015.
For Profumi di Lamole, if you're on Facebook, I'd recommend you follow their page: https://www.facebook.com/profumidilamole to get updates directly.
Same for Radda nel Bicchiere - http://www.raddanelbicchiere.net/
both were held on the same weekend this year (May 31-June 2), it's possible they might choose to do the same in 2015 as June 2 is a national holiday and in that case makes it possible many might make it a long weekend (as June 2 is a Tuesday, they might take Monday off too ;-))
The wine festival Profumi di Lamole is one of my favorite early summer events ... that and the wild boar sagra in the local mountains...
It is very small - so don't expect tons of people and/or selection of wines. If you are going to want to eat there you should really make reservations at the restaurant and then be prepared to take it slow. The other option is you can enjoy the food stand. The fare is simple and classical. Normally it includes plates of local salumi & cheese, maybe a few types of panini with prosciutto and I believe last year they had panzanella (the bread salad with fresh tomatoes, cucumbers and lettus). I actually found it rather nice because I could mix and match the wines at the stands with the plate I was eating. They provide some tables and chairs in the shade close enough to get up and change wines several times ;-)
And some of them had vin santo (the sweet or dry dessert wine) so I remember we got an order of biscotti (cantucci) and tried that as well....
just don't plan on driving anytime soon after all that wine tasting....but when you do, the road up and back to Lamole (curvy and picturesque) has several breathtaking views not only of the vineyards but of the gigli (lilac colored iris flowers) in bloom - be ready to take lots of pictures.
If you are going to be in Tuscany in June there is also the Montespertoli "Mostra del Chianti" that in 2015 runs from May 30th to June 7th. You could work it in around the Lamole and Radda ones.
Montespertoli is 30 miles southwest of Florence, a few miles off the main highway to Pisa, the FI-PI-LI. You take the Ginestra Fiorentina exit. This festival features high-quality wine from local producers and because it runs for over a week it also has other delightful activities during the course of festivities, food stands, concerts, live music, open-air theatre, parades, and an open-air restaurant in the main piazza.
This is a very pretty, hilly part of Tuscany, less dramatically mountainous than the main "Chianti Classico" area. It's worth a trip out this way from Florence to take in other nearby places such as Certaldo Alto (birthplace of poet Boccaccio), San Gimignano (for their famous Vernaccia white wine) and Colle di Val d'Elsa.