You can start investing as soon as you have money in your brokerage account.
Once your brokerage account gets approved (you will be notified), you will fund that account by doing a bank transfer from your domestic account. Stockal works with multiple domestic banks to make the process easy and seamless for you and also to get you very low forex rates. You can do all this sitting at home or office. Then it takes 2-3 business days for the transferred money to reflect in your account. You can start investing immediately afterwards.