It was super easy to get this thing going following the tutorial by stevohen!
I made a variation in the firmware, so that the bed leveling grid is 4 by 4 instead of 3 by 3, it's a little more accurate and I prefer it that way!
I also modified the bed leveling script so that the grid is precisely in the center of the bed, and here it is:

G28 ; Home all axes
G29 L45 R190 F45 B190 ; Perform ABL on grid 45mm inside limits
M500 ; Save bed levelling to EEPROM
G1 Z40 ; Lift Z to wait for heating

Feel free to edit it to your liking!

At last, here is my Ender 3 Custom Start G-code:

M0 Insert Z Switch ; Insert switch and click to continue
G28 ; Home all axes
M420 S1 ; Enable Mesh Bed Levelling
G1 Y-{machine_depth} Z40 F1000 ; Move Heat Bed back and lift nozzle

; Heat up settings. Important to have here, AFTER homing sequence!
M140 S{material_bed_temperature} ; Start heating bed
M0 Remove Z Switch ; Remove switch and click to continue
M190 S{material_bed_temperature} ; Wait heating bed
M104 S{material_print_temperature} ; Start heating extruder
M109 S{material_print_temperature} ; Wait heating extruder

G1 Z20 F100 ; Slowly lower the nozzle to give you a headsup that printing is starting

G92 E0 ; Reset extruder
G1 X20.0 Y20 Z0.2 F5000.0 ; Move to start-line position
G1 X20.0 Y200.0 Z0.2 F1500.0 E15 ; Draw 1st line
G1 X20.4 Y200.0 Z0.2 F5000.0 ; Move to side a little
G1 X20.4 Y20 Z0.2 F1500.0 E30 ; Draw 2nd line
G92 E0 ; Reset extruder
; End of custom start GCode

Here's a video of the bed leveling https://youtu.be/yClIl7IMeRg

Creality

Ender 3

No

No

0.2

40%