Broadbeans poking through!!

Thanks guys for all your previous advice. Having put the broadbeans outside in pots under a plastic cover, they are finally pushing through.(They took ages though) How long should I wait before planting them in the ground someone told me wait until they have 4-6 true leaves? If they have been sitting outside, I take it I dont have to harden them off? Thank you and look forward to hearing from you!!