Nearly every DOT and HOT that I have tested gave an initial real tick. However, the first tick was invisible. By that, I mean it didn't show up in either the combat log or on the screen, but it still healed or did damage.
Every rogue bleed I tested also had a similar result. However, it isn't universally the case. At least one HOT that I tested gave the number of heals that it displayed.
I had written a bug report about it a while back. This is part of the report:
I wanted to make a thread since many people have noticed they lost the first tick on these types of skills again.
The piece of info that I can add is that per some minimal testing on a couple combos, these skills don't appear to be as broken as that. I was playing around with a R/M since I wanted to see if Poison Trap had been changed since it was fixed. It took 3 ticks to kill the mob I used it on, except that only 2 ticks showed up on screen and in the combat log. In other words, the first tick is there, it's just invisible. R/M also has another DOT Poison Flame, same result. Then I flipped over to R/P and changed some gear around so I had some "damage" and tested Regeneration. Same result. 10 ticks of healing to my HP but only 9 showed up on screen and in the combat log. I checked another couple class skills too.
I've tested quite a few other skills since then. As far as I have been able to see, very few are actually missing the first tick.