Are analytics essential before launching?

Good question.

If you spend the extra time adding analytics but nobody downloads the app, then the extra time would see to be a bad idea.

If you don't add analytics and your app is a hit with a sizable number of downloads/users, you'll miss out on metrics that can help guide your next iteration. Worst case, you lose users and won't have data on possibly why they left.

I recommend adding basic analytics to capture how often the users open your app and how long they spend using it. That will hopefully take less time to implement (just add events for startup and shutdown.) You could then add more granular analytics later.

With an app on the app store, you have the benefit of getting some metrics from Google Play itself, so at least you know how many people have downloaded the app.

I'd say it depends on how you plan to evaluate whether the app was successful or not.

What measure(s) define success to you for this app? # of downloads? # of emails collected? Revenue? Or is it a beta launch just to get feedback?

If you only have a handful of users to start, and have their emails to get feedback from them, that's a good way to get initial feedback. If that's what you'er going for, the analytics can probably wait until post-release.

If you expect some traffic upfront, build them in first. They're most valuable when you've got a fair bit of usage in the app (otherwise there's not enough data to make decisions with).

If you do delay adding them, don't delay too long though. Once you're getting even a little traffic they're incredibly valuable.

I’d try to capture the one super-important metric that will help you determine if your product is providing value. Number of downloads, installs, time in use, and uninstalls are fine and should be known, but none of those tell you why people use or don’t use it.

Your app has a special “North Star” metric that’s different from other apps. This number or observation is the key indicator of value provided, so if you can’t track it somehow, you’re kinda operating blind.

If you’re building a daily habit tracker, you’ll want to know if folks are checking stuff each day. If you’re building a directory list, you’ll want to know that people are clicking through to the list items. Not sure if I’m explaining this well...I just woke up :)