Depends when you normally see your last frost. The weather is unseasonably warm right now but could easily go back on itself. I'd give it another week or two where you live. For us it is the end of the month.

I live in Derbyshire and I have had my runner beans and dwarf beans planted out for 2 weeks now. If there is a frost threatening I cover them over with some old bedding sheets and peg them in place to the canes and strings. They havn't suffered yet. I did this last year and even on a really bad frosty morning the only damage I got was a touch of frost burn on the edges of the leaves closest to the sheet, but I didn't lose any plants and they cropped really well.

I live in cambs and planted out a week ago thats only because i was late potting my seed this year otherwise i would have planted out sooner especially if your veg has the advantage of early morning sun as well as midday.

I live in West Wales and mine have been planted for over a week. If you are worried there might be a frost you can make mini cloches by cutting the bottoms off plastic coke bottles. Leave the screw caps off for ventilation.