It's not too early to start thinking about using your culinary herbs. You can take cuttings to use fresh as soon as the plant becomes established. You can also freeze or dry culinary herbs so you have them to use after the growing season is done. I have already harvested tarragon, oregano and lemon balm which are now drying on my drying rack. Vigorous growers like these can be harvested at least three times throughout the season.
Speaking of lemon balm, many people are distressed at this fragrant plant's ability to spread rapidly. Although it is in the mint family, it doesn't spread by runners like spearmint, etc. When people complain about lemon balm going everywhere, I always think much of it is due to reseeding. The p!ant is perennial, and will increase in size each year, but if it's getting out of hand and going everywhere, it may be due to seeds dropping. Lemon balm has small, white flowere which are not particularly attractive, so remove them before they turn into seeds. If you can plant it in a corner or against a barrier, that will help contain its vigorous growth.
Lavender's first and best bloom time is in June. Harvest lavender flowers while it's still in bud. Eventually, each bud will open into a floret. However, these florets eventually fall off, so you'll lose a lot of fragrance by harvesting after flowers open.
Varieties of English lavender and hybrid lavandins are hardy here in zone 6. They're all fragrant, but the main differences are in size of the plant and flower color. Compact lavenders are 12-15" tall with shorter stemmed flowers. Mid-size are 18-20" tall and tall varieties have foliage about 24" with the flowers standing above that. Compact varieties we carry have purple or pink flowers, mid-size have lavender blooms and tall varieties have purple or white flowers. Lavender plants like lots and lots of sun, very well-drained soil and soil with a little higher ph. Mixing in a little lime when you plant lavender is a good idea.