There are two things that determine how long it takes to bloom a Paph from seed. One is the genetics of the individual paph seedling you have. The second is the skill of the grower.
. To the first point, if you bought a batch of 25 seedlings, and if you grew them well, in all likelyhood a couple or so seedlings would gallop ahead of the pack and bloom a year or more earlier than the main group of seedlings. Then there would be the main group blooming, then as much as several years later the stragglers would bloom. This is normal. Now when you buy a single Paph seedling, it is hard to know whether you have a 'leader', 'middle of the pack', or a 'straggler'. There is no fixed answer, you just have to grow it and see. Some Paphs, especially the bigger ones are slow growers. It is very normal for growers who use standard growing techniques, for Paphs stonei and rothschildianum to take minimum 5, often 7 or 10 years to mature. Some Paphs such as Paph Maudiae, can be bloomed from seed in as little as 3 years. It all depends on genetics, there are tendancies for certain species & hybrids, but there is no absolute fix time period.
. Second point. If your culture is less than ideal, it will take longer to bloom your Paphs. If your conditions are ideal, you can match or beat the times published in the books or on the forums. I have a Paph Transvaal in bloom today, that I bought as a seedling in 1991. This is the first time it has bloomed for me. I have been watering it for 17 years. It should have bloomed 15 years ago, but several times over the years I would rot roots off, or dry it out too hard, or not give it enough light, or something. I would get it close to blooming size and then screw something up, set it back and have to start over again. Each time it would take 3 or 5 years to get it back to where it was before I made the last mistake. Today it is in bloom because for the last 5 years I have met or exceeded the bare minimums of its needs. And like an idiot, I forgot that AOS Judging was Saturday and I could have shown it. I may be dead of old age before I bloom it this well again. Oh well, I have shown it to a few friends, that counts.
. So the interplay between your growing conditions and the specific genetics of the seedling you are growing is the reason that you should not put much stock in statements about how long it will take to bloom something. It is guesswork. The plants bloom when mature and happy, however long it takes.