When is the right time to kiss her?

i will go out with this girl i had realised that she likes me but scared of me a bit and always want me to the the actor, we will have lunch together and then have a walk in the park at night presumably. I real wanna kiss her that day to show her that i like her but the issue is when will i know is the right time to do it, I am just wondering if there are some signs that girls show during this time. I wana make sure i kissed her at the right time and she will want it that time. Thanks a lot.