Bradford Pear grafting timing

[ToddG]

I have about 6 bradford pears I want to bark graft this spring. I am in zone 7A and I went out today and noticed the bradfor pears were starting to bloom. Should I wait for leaves to start coming out before grafting? What happens if they leaf out early and I go ahead ang graft but get a frost afterwards. This is my first try at grafting and would appreciate any info.
Thanks,
Todd

 

[Turkey Creek]

They will take now, but if you feel like you might get a killing frost yet it wont hurt to wait a bit longer.