There are three ways:

1. wait_for some time after executing kubeadm init ansible task.

- hosts: master
  become: yes
  tasks:
    - name: initialize the cluster
      shell: kubeadm init --pod-network-cidr=10.244.0.0/16 
    - name: sleep for 20 seconds
      wait_for:
        timeout: 20

2. Make use of until in ansible.

- hosts: master
  become: yes
  tasks:
    - name: initialize the cluster
      shell: kubeadm init --pod-network-cidr=10.244.0.0/16
      register: result
      until: result.stdout.find("Your Kubernetes master has initialized successfully!") != -1
      retries: 1
      delay: 20

NOTE: Here we retry kubeadm init until we get the string Your Kubernetes master has initialized successfully! in the output.

3. Check if the file /etc/kubernetes/admin.conf exists after executing kubeadm init ansible task.

- hosts: master
  become: yes
  tasks:
    - name: initialize the cluster
      shell: kubeadm init --pod-network-cidr=10.244.0.0/16
    - name: create .kube directory
      become: yes
      become_user: ubuntu
      file:
        path: $HOME/.kube
        state: directory
        mode: 0755
    - name: Check admin.conf file exists.
      stat:
        path: /etc/kubernetes/admin.conf
      register: k8s_conf
    - name: copy admin.conf to user's kube config
      copy:
        src: /etc/kubernetes/admin.conf
        dest: /home/ubuntu/.kube/config
        remote_src: yes
        owner: ubuntu
      when: k8s_conf.stat.exists

NOTE: Here we execute admin.conf copy only when the k8s config file /etc/kubernetes/admin.conf exists.