This gist shows how to calculate the diff in seconds between host UTC time and Google Cloud remote machine creation UTC time and use it to wait_for SSH only if the machine is new to avoid being blocked by SSH Guard

rfc3339.py

#!/usr/bin/python
import datetime

class FilterModule(object):

    def filters(self):
        return {
            'rfc3339_to_utc': self.rfc3339_to_utc
        }

    def rfc3339_to_utc(self, rfc3339_date):
        # Test
        # f = FilterModule()
        # assert str(f.rfc3339_to_utc("2019-10-08T16:39:57.097+07:00")) == "2019-10-08 09:39:57"
        # assert str(f.rfc3339_to_utc("2019-10-08T16:39:57.097-07:00")) == "2019-10-08 23:39:57"
        date, time = rfc3339_date.split("T")
        op = "-"
        if "+" in time:
            op = "+"
        time, offset = time.split(op)
        offset_hour = op + offset.split(":")[0]
        dt = "T".join([date, time])[:19]
        dt = datetime.datetime.strptime(dt, "%Y-%m-%dT%H:%M:%S")
        dt -= datetime.timedelta(hours=int(offset_hour))
        return dt

wait_for.yml

# ################################################
# start seconds_since_instance_creation
#
# This fact is important to avoid random SHH Time Out!
# wait_for SSH if done too many times will block host IP (ie, experimenting on playbook)
# because it will think that it's an SSH attack, given that this call to SSH doesn't provide credentials.
# This param will be used to run wait_for just if the instance was created recently. If not,
# we will asume SSH is already running and skip

- name: host_dt_now_utc
  set_fact:
    # -u param in date returns UTC datetime on host. Then parsed to dt with no timezone info.
    host_dt_now_utc: "{{ ( lookup('pipe','date -u +%Y-%m-%dT%H:%M:%S') | to_datetime('%Y-%m-%dT%H:%M:%S') ) }}"

- name: gcp_rfc3339_to_utc
  set_fact:
    # GCP machines return their timestamps in rfc3339 format containing timezone info. 
    # This custom filter will return a python datetime in UTC with no tz info.
    gcp_rfc3339_to_utc: "{{ instance.creationTimestamp | rfc3339_to_utc }}"

- name: seconds_since_instance_creation
  set_fact:
    seconds_since_instance_creation: "{{ ( host_dt_now_utc | to_datetime - gcp_rfc3339_to_utc | to_datetime ).total_seconds() }}"

# end seconds_since_instance_creation
# ################################################

- name: Wait for SSH to come up
  wait_for: 
    host: "{{ instance.networkInterfaces[0].accessConfigs[0].natIP }}"
    port: 22
    delay: 5
    sleep: 5
    timeout: 100
    state: started
  when: "seconds_since_instance_creation|int < 240"