Another question about Buzz Bombs (V1's)

In this thread about the V1 (buzz bombs) and V2 attacks on London during WWII, there is a link that states that the V1 attacks commenced on June 12, 1944.

Is it strictly a coincidence that this occurred within a week of D-Day, or was it Hitler’s revenge for the invasion?

This page says

but on this page it says

and this page says

It looks to me like D-Day definitely spurred the Nazis to commence V-1 attacks, but even without the Allied landings, it seems likely that there would have been V-1s hitting England sometime in the summer of 1944. On the other hand, it does seem possible that V weapons could have been launched even earlier than that if they had been given higher priority–if you can believe Speer.