Alright, you seem to already have the correct keymap file in DEVS:keymaps/, as you seem to be able to use the Keymap in Workbench programs. That's good (otherwise you would have had to copy it from "Extras 1.3:Devs/keymaps" to DEVS:keymaps/).
Now open your Workbench disk and start the Shell. In the Shell, type:
This will bring up a ...
No, you can and, more importantly, it is fully supported to run Workbench 1.3 on a Kickstart 1.2 machine.
This was rather common back at that time, because Workbench 1.3 brought some nice new features (like the RAD: drive, better printer drivers), and at least in Europe the first batches of Amiga 500 and Amiga 2000 arrived still with Kickstart 1.2.
You should start by adding your chosen commands to S/User-Startup on your boot volume. You can also refer to it as S:User-Startup; S: will redirect to the S directory on the boot volume. This will definitely work on Workbench 2.04 and later, and may also work on earlier versions too (some application software "backports" the necessary support to Workbench 1....
At startup, the Amiga used a timing routine to check the frequency of the AC power supply, and start in PAL (50 Hz AC) or NTSC (60 Hz AC) appropriately. Unfortunately, the detection was buggy, and sometimes 50 Hz was wrongly identified as 60.
Many Europeans would have Declan McArdle's NoPALReset in their s:startup-sequence to avoid this. I think the problem ...
In general, booting an Amiga from an HDD is quite fast, and can certainly be far less than 30 seconds even when a significant number of drivers and small applications are loaded via commands in S:Startup-Sequence.
It should normally take only ~5 seconds to initialize the hardware and see the display of the CLI window (see below about cold vs. warm boot times)...
With a spare megabyte of RAM you could also install Workbench or equivalent in a resident bootable RAM disk ("RAD:"), so you could boot from RAM with no moving parts.
Of course that will only work for a warm boot/warm start, not the first "cold" boot.
Some details here: https://www.amigareport.com/ar139/p1-6.html
Another factor is the SCSI ID; make sure your HDD is set to 0, and set a lower number than std. in HDToolBox for max. ID, as low as possible, and save the new info to your drive.
That way, the SCSI adapter will stop searching for drives as soon as it can, speeding things up a bit.