To simplify this for all involved:
G1 Learner's Licence - For all, irrespective of driving experience. This is a written test, which is straightforward.
G2 Licence - For those without any international driving experience, wait time of 12 months after G1 before you can attempt G2. If he/she completes a learner's course from a govt. certified institute, wait time reduced to 8 months. For those with 12 or more months of driving experience, they can directly go to G2 without any wait time.
G Licence - Here's where the driving extract comes in. If you want to skip wait time between G1 and G or G2 and G (if you avoid G cuz you aren't confident about attempting a highway test), you need the extract. Otherwise, there is a wait time of a year to get to G. If you have an international licence with more than 12 months of driving experience but no extract, you can attempt the G2 after the G1 immediately, but wait to attempt G for 12 months.
If you are okay with no alcohol in blood, working seatbelts = number of passengers in car between midnight and early morning, and slightly higher insurance amount (in case you buy a car), G2 is fine for most.