Found chart referenced recently in 2020 and back earlier in 2009 swine flu days….
https://www.uncovercolorado.com/wp-content/uploads/2020/03/spanish-flu-death-chart-1918-19-europe-america.jpg
https://symonsez.wordpress.com/2009/10/25/obama-declares-swine-flu-national-emergency-has-1918-spanish-flu-returned/
Transit time then fastest likely 4 days, but during war and threat from submarines likely more like 16 to 18 days, course changes and all and governed by speed of ship slowest in convoy.
So how did Paris, London, New York, and Berlin peak near same time?