- Wait for ASRouter to be initialized before recording screen impressions to ensure the impression for the first screen in `about:welcome` isn't lost because ASRouter's `_storage` variable is still null
- Local testing shows that this first screen impression is lost when an attempt is made to record it before ASRouter is initialized. It's unclear if this is an issue on production, or just when running locally. Locally the issue occurs consistently, but this can't be the case on production as telemetry includes impressions from the first screen of `about:welcome`. However, we should monitor telemetry for possible changes after this fix goes out to see if there is an increase in screen impressions for the first screen of about:welcome.
Differential Revision: https://phabricator.services.mozilla.com/D232736
d7704cbe37