Yes, once you have configured data to be approved, and hidden in analytics, then any past, unapproved data will be hidden the next time you rebuild analytics.
Note that when you define an approval workflow, you can choose the period type. So for example, even if your data set is monthly, you could approve quarterly. This means you wouldn’t see the data in analytics until you approve the whole quarter, but it means you have to make fewer approvals.
Also note that you can choose the level(s) for an approval workflow. So if you approve only at the district level, you won’t see any data from the district until you approve the whole district. But it also means that you have to make fewer approvals. At the extreme, if all you want to do is hide the data for a period until you are ready, you could define the approval level at the root (lowest-number) organisation unit level.
If you need to approve past period data in bulk, and you still need many approvals for different periods and/or organisation units, you can try using the Web API. You can see what Web API calls are needed by reading the documentation here here or by approving something through the front end (pre-2.33) and looking at the http calls (for example in the Chrome browser select View -> Developer -> Developer Tools.) You can execute the Web API calls using curl, or your favorite programming/scripting language.