When should i stop saving and start to invest? Is there a minimum amount i should have before i start investing?

Hello!
Instead of asking how much to save before investing, maybe you can look at it from another perspective in terms of ensuring that your high-interest debts are paid off before investing. The recommended amount of savings would be about 6-9 months of your emergency funds in order to ensure that you will have enough savings should anything happen to your job.

It is important to pay off all your high interest debt first so that you would not inccur too much interest.

I personally feel that once you have done these few things it would be the best time to start investing. You should try to do this as soon as possible as investing early as possible would be the ideal situation due to compounding.

I would just answer the first question to add on to what Zann Chua said.
I am curious why do you want to stop saving? Why not both at the same time? There are a lot of reasons why you should save and what you want to save for. Just how much much do you want it to be?

Starting investing could be easily done with regular saving plans on Sti etf. While at the same time, you gather knowledge on how to invest. Most or all investing are started with researching and analysis of companies (famous investors mentioned at least 90%). The rest 10% is patiently waiting for a chance to act.*
*Sourced from famous and experienced successful investors, like Warren buffet. Totally have no intention to copyright. After doing my homework that I find myself that learning is infinite.