Congratulations! Motherhood is such an amazing journey.
Here are my answers to your questions:
1. As soon as you found out you're pregnant.
2. Better ask your doctor about it. There are some mums who have delicate pregnancies thus it is important to give the head's up from your doctor if it is safe for you to travel. Be also mindful that first trimester is very crucial for a growing fetus, thus, you need to take extra care.
3. Avoid eating junk. You are growing another person inside your body and it is important that your body functions well. Eating junk can lower your immune system, increase your sugar and salt levels. So be mindful of eating processed food.
God bless your journey to motherhood! Cheers!