Not exactly. The temperature of the hob is not a useful guide to its energy input capability. The area under the pot will be cooled by the pot’s presense. The hob won’t be a constant temperature device (even it it is thermostatically controlled) - at least not enough to be useful in such an estimate.
What you need is the power of the hob and an estimate of the energy loss (convection mostly) in the system. Condutivity of the hob to pot is probably not an important issue, but in principle should also be facored in. Then you need to work out the specific heat of the system - which allows you to work out when it reaches boiling point. So, mass of the pot, knowledge of the material the pot is made of (probably aluminium) plus volume of water. This still isn’t brilliant because the pot won’t heat evenly. Because the specific heat of the water will dominate anyway, you could probable get a good estimate by simply working out the power input and the specfic heat of the water. Easy. But not exactly accurate.
In truth the simplest, and by far and away most accurate, thing to do is to time it once. That takes into account everything. You are already assuming that from one use to the next the system is reasonably constant.