For 1 betta (unless you've changed your mind?) 1 ppm is plenty. That's all I used for my betta in a tank smaller than yours.
Remind me - the feathery looking plant, is it live or fake? If it's live I reckon that between the plant and the Safe Start you should be OK to get fish once ammonia drops to zero. But that depends on whether you can actually manage to go to a shop to buy fish at the moment. If you can, do a big water change once you hit zero, then go shopping. If you can't, add a tiny bit of ammonia once a week and when the shops open again, do the big water change and go shopping. You used 24 drops to get slightly over 3 ppm, so 1 or 2 drops ammonia once a week is enough.
Remind me - the feathery looking plant, is it live or fake? If it's live I reckon that between the plant and the Safe Start you should be OK to get fish once ammonia drops to zero. But that depends on whether you can actually manage to go to a shop to buy fish at the moment. If you can, do a big water change once you hit zero, then go shopping. If you can't, add a tiny bit of ammonia once a week and when the shops open again, do the big water change and go shopping. You used 24 drops to get slightly over 3 ppm, so 1 or 2 drops ammonia once a week is enough.