Drupal 8 is in the beta releases stage getting closer to supporting an upgrade path. It is still in development and there are still some interface changes expected. As per the beta changes policy interface string are unfrozen and user experience improvements are prioritized. On the other hand, I don't know of major initiatives to change the interface strings and I believe most of the interface should be considered stable at this point.

As we are getting close to releasing beta versions with support for the upgrade path, that means more sites will start to use pre-release versions of Drupal 8. This helps find bugs and we would love the multilingual system to be (even more) thoroughly tested as well. We need translations for that to happen. We also need translators to look at source strings, so they submit issues found in them.

So while the user interface is not yet frozen, there are various good reasons to start translating Drupal 8 now. How fast should you plan to complete translations? Strings will likely be frozen with the first release candidate (which is cut when there are no more critical issues against Drupal 8). However that release candidate may become a release if no more critical issues found as early as a couple weeks after, so starting translation at RC1 would be too late to be ready for the release. You should consider starting sooner than later.

To make that process easier, we introduced a new Drupal 8 translation status page at https://localize.drupal.org/translate/drupal8 which lists the languages by completion status based on the last exported Drupal 8 translations available. Congratulations to the Spanish, Danish and Finnish team for being the top three! We also made it easy to access the multilingual demo from that page and included some advice on translation readyness as well as a step by step guide to new contributors.

You are encouraged to start translating Drupal 8, organize local translation sprints and test your translations by installing the new version in your own language. Big Drupal events like DrupalCon Bogota host multiple days of sprints where translators should join and take their space. The next big event coming up in Europe is Drupal Dev Days in April with a week of sprints.

All of the new Drupal 8 APIs should be supported now on the site including default shipped configuration. If you find something on the Drupal 8 user interface that is not translatable, submit a Translation template extractor issue and tag with "Drupal 8 compatibility".

Balu Ertl collected a list of 1200 "easy" Drupal 8 strings to translate to your language. These are 1, 2, 3 or 4 words long.

One final tip to get started faster. Localize.drupal.org does not (yet) support matching of strings that slightly changed from Drupal 7, however it brings in exact translations of modules that were added to core, such as Views. To match slightly changed strings, you can do the following:

1. Download the complete Drupal 7 translation of your language.
2. Using the Export tab on your language, export a full translation template (with untranslated and translated strings included) of Drupal 8.
3. Use the gettext msgmerge tool to find fuzzy matches locally.
4. Review and correct the translations locally.
5. Finally import the new translations to the site with the "Multiple contributors" user for proper attribution.

Thanks for making Drupal 8 happen!