At Verko, We have provided two Under Construction Page :

You can see the v1 here -> http://dahz.daffyhazan.com/verko/under-construction-v1/

You can see the v2 here -> http://dahz.daffyhazan.com/verko/under-construction-v2/

You can use this page when you’re developing your site

1. Install this plugin : Restricted Site Access

2. Activate the plugin.

3. Go to Settings > Reading.

4. You will find new option as you can see in below screenshot :

5. Choose your under construction page from Handle restricted user dropdown list.

6. Your non-logged user will be redirected to that page, you can access entire page with login, and you can deactivate the plugin if you think your site is ready to launch.