I decided to write my own answer since I don't agree with the one that already exist.
I tested respawn of Baleful Bunnies today for some time and in my opinion it absolutely does not depend on the time in Tibia. I was killing bunnies during day and night.
So the result of my test looks like this:
XX:10 - the end of the raid
XX:21 - start of the raid (after 11 minutes)
XX:31 - the end of the raid (after 10 minutes)
XX:43 - start of the raid (after 12 minutes)
XX:55 - the end of the raid (after 12 minutes)
XX:06 - start of the raid (after 11 minutes)
XX:19 - the end of the raid (after 13 minutes)
I tried to make as accurate stats as possible, but believe me, it's hard on a crowded server, so please take into account that results may vary about +/- 1 minute.
Generally raid of Baleful Bunnies takes 10-13 minutes and the break between raids takes also 10-13 minutes.
Exact locations where you can find Baleful Bunnies you can find here:
Note, that you can meet Baleful Bunnies and Bonny Bunnies alternately!
In practice it's like: sometimes I meet 2 Bonny Bunnies, sometimes one Baleful and one Bonny Bunny, sometimes two Baleful Bunnies, or only one Bonny/Baleful Bunny... finally we can meet none of them in presented above places.
Worth to mention, that you can block the spawn of bunnines on a particular location by standing there. I tested it on the most eastern location next to the tree and none of bunnies appeared around me.