Most of the JWs I've spoken to immediately say 1914, adding that no
other religion was able to pinpoint that date except them. They were
very proud of that accomplishment.
It's always worth bearing in mind two points on this.
1. They expected armageddon that year. They believed the last days began in 1799, 1914 was the endpoint.
2. They expected things to finish in October 1914. In June 1914 Archduke Franz Ferdinand was assassinated then on August 4th, 1914 WW1 really began. There was no similarlity between their predictions and start of WW1. They pinpointed nothing.
The whole 1914 thing is a classic case of serendipity - a "fortunate happenstance". The WT has eaten out on it ever since.
I wonder how many of our parents/grandparents/great grandparents came in because 'they got 1914 right'...