It depends on what you’re trying to accomplish with the workout. If you were doing 30m flys, there are plenty of threads around talking about more gradual acceleration that allows you to reach a higher MaxV in the fly portion. In this case, you would want to start from standing and a longer leadin than 30m. Block starts here are definitely not what you want to do–not any different than doing 60s in that case.
And it does look like you came up too quickly for a 10.2-10.4 guy.
But most people do 60m flys to work on their finish (speed maintenance after the MaxV). In this case, your leadin is shorter, you don’t necessarily reach MaxV right at the beginning and what you’re trying to work on is holding onto the MaxV after it occurs. So, here, the blocks aren’t quite the same impediment to the workout that they hare in 20-30m flys.