Slim...
1919 does give them more time than 1914 because it is not tied fo “this generation”.
1919 simply marks the re-establishment of pure worship and the endtime can stretch from that date indefinitely.
Keeping 1919 affirms the authority of the GB-faithful slave chosen in that year, without tying them down to 1914-generation teaching.
For example Seventh Day Adventists believe the endtime and investigative judgement began in 1844 and continue to stretch this out.
But still Satan has a "short period of time" from when he was thrown down to the earth, which they still teach is 1914. If they ever change 1914 as not the birth of the kingdom or the start of the signs of the last day with Satan on the earth they are in a world of pain as that affects a lot of their teachings.
I agree they are trying to mention 1914 less and more on 1919 but the reality it that it doesn't change much.