you should get better light on it before you switch to 12/12. if your going to repot it you should also do that before you switch your lights to 12/12. you don't want to stress that plant too much as it starts to flower. your plant looks healthy, it just needs more light and you will see a lot more growth. as for the mg, if it is what is available to you then yes it can be used, just use very little at a time. use the all purpose or the tomato version of mg for veg, and then if you want you can switch to the mg bloom booster in flower. try adding some epsom salts and superthrive for a more complete feeding. both of those items are readily available everywhere there is mg in the u.s. but I don't know about over seas. good luck with your grow man.