No, he wasn't the first. The Buddha beat him to it by about a millenium.
The three lifetime idea, along with the ‘relative truth’ of rebirth, is Brahmanism, eternalism. Buddhagosa was originally a Brahman, and along with the eternalist view of Paticcasamuppada he also ‘endorsed’ other Vedic practices as part of Buddhism, e.g. meditative practices that are totally irrelevant to the cessation of suffering, and quite a few other ideas (although he was not the first to endorse such a view and such ideas).
Those who wish to characterize rebirth as a brahminical import into the pure Buddhadhamma would have to account for the numerous times the Buddha explicitly teaches it. Likewise, the strongest case for the "three-lifetimes" model is found in the suttas themselves, where the factors of "birth" and "death" are routinely defined in the literal terms of actual birth and death of beings, not in the metaphorical sense necessary for the momentary model, which is rather contrived for this part of the cycle.
As for the various practices described in the Vissudhimagga "totally irrelevant to the cessation of suffering" I can only infer Apichato is referring to the forty samatha meditations, such as mindfulness of breathing and kasina work. As far as I know, there is no practice in the Vissudhimagga that isn't found previously in the words of the Buddha himself. This is not surprising, as the VM was written as a commentorial encyclopedia, a precis of the canonical teachings. And while samatha meditation does not lead by itself to cessation of suffering, it is far from irrelevant to that endeavour. You have to practice your scales if you want to play at Carnegie Hall.
Lastly, dismissing a teaching as a "relative truth" implies a basic misunderstanding of that term. A relative truth is not a falsehood. In the case of rebirth or kamma, these teachings may be called "relative" because they are stated in terms of individual beings which in the ultimate sense are only conventional names. However, this does not mean they do not actually happen!
POSTSCRIPT ON COMMENTING POLICY
I've fiddled with the settings for the comments again, here is the new deal;
1. I've left on word verification. I know it's slightly annoying but less than having the comments fill up with spam for great stock tips and male enhancement products.
2. I've taken off moderation, we seem to have lost the nasties. If they come back, moderation will go back on.
3. Lastly, I've enabled the requirement that you register. We've got a lot of anonymous postings and it makes it impossible to follow any discussion in the threads. Registration with Google seems to be the only way to require posters to use a name (doesn't have to be your real name.) If you have a blog, or use other personalized Google services, you're already registered. If not, it's free and easier than most on-line registrations. We may lose a few posters doing this, but I think it will make the comments more readable for everyone.