How do I prevent my Elastic Beanstalk app from showing as unhealthy if my post deploy takes a long time?

I my .ebextensions/00.command.config, I have:

container_commands:
  00_download_models:
    command: "./download.py"

In download.py, I have some code that downloads a lot of files (around 20GB). That takes time and I'd like that to finish before Elastic Beanstalk attempts to boot my app. But in /var/log/web.stdout.log, I see:

Jun 27 19:42:46 ip-172-31-46-211 web: [2020-06-27 19:42:46 +0000] [3997] [INFO] Worker exiting (pid: 3997)
Jun 27 19:42:46 ip-172-31-46-211 web: Loading generator
Jun 27 19:42:46 ip-172-31-46-211 web: using device: cpu

Loading generator is what I print in my application.py. This is a flask app, if that matters. It appears to attempt to restart the app multiple times while downloading.

What can I do to first finish download.py, THEN attempt to start the app?

In EB, you can disable health checks during deployments. For example in console you can do this as shown in the screenshot:

Obviously, you can also do it form CLI if you use it for deployments.

They still may show as unhealthy, but won't lead to failed deployments.