How long would it take to build a city like KL in RL given roughly the resources Aegon I had and would this change depending on the layout (hub-and-spoke vs. grid)?

In real life, it kind of depends. To take London as an example, there have been periods of extremely slow growth and periods of outright decline – Roman London was 35,000 strong whereas it was down to 18,000 by the time of the Domesday Book – but there have also been periods of extremely rapid growth. For example, by the end of the 15th century, London was only 60-70.000 strong and by 1600 it was up to 250,000 residents, and by the end of the 17th century was up to 600,000.