Tomorrow at 12:20 UTC, the BCH fork will happen. But will it? We can only talk about a forked chain once a block has been mined on the other chain that is incompatible with the original chain. In this case, BCH has a "first must be big" condition that requires the first block mined by BCH miners to be >1 MB, so that it won't be valid on the BTC chain and the fork is guaranteed.

But how long will it take for this block to be mined? BCH will have a mechanism that allows for the difficulty to be lowered when hashrate is very low, but this mechanism works by checking the total time that was used to mine the last 6 blocks. If this value is more than 12 hours, the difficulty is adjusted by 20%.

The problem is that this only activates once a block has been mined on the BCH chain. That means that if the number of miners is very low, it can take a long time (1% of the total hashrate -> ~16 hours for the first block).

The next block will have a 20% lower difficulty, but this isn't a massive change and the second BCH block will still take a long time. Fast-forward, once the total time for the last 6 blocks reaches the 12 hour mark (this happens after 2-3 days according to my back-of-the-envelope calculations), the most recent block was mined approximately one hour after the one before. At this point the extra difficulty adjustment mechanism deactivates and the blockchain keeps going on the way it's been going.

That means that there'll be anywhere between 1200 and 1300 blocks left to mine in the current regular difficulty adjustment interval for BCH. At 1 hour per block, that's about one and a half months.

Did I miss something? Or is BCH really going to be limited to a handful blocks the first few days (with the first block possibly as late as 1 day after the actual t-0), followed by multiple weeks of 1-hour blocks?

As a consequence, the first blocks of BCH will be very full with people trying to split their BCH from BTC and moving BCH to exchanges. Even though BCH blocks can go up to 8 MB, the BCH network will be far more congested than the BTC network (which is somewhat ironic, I guess).