Hi Aparna,

1. If you've purchased a bag of potting soil/mix then that is all you need to start your seeds. When you transplant your sprouted seeds to a bigger pot or in ground, you can add all purpose (it will have the same ratio of N-P-K on the bag/bottle like 4-4-4, 16-16-16) plant food to the pot or the hole before you put your plant in. You can also use water soluble/ liquid fertilizer on your seedlings when the second or third sets of leaf have sprouted before you do your transplant.

2. The time is now. (Indoor or outdoor for certain types of veggies). You want to start your seeds 2-3 weeks before last frost so, by the time your seeds have a few leaf on them the weather will be warmer for them to be transplant outside

3. If you want to sprout your seeds before you plant, you can do it by soaking in water overnight or old fashion damp paper towel method. Beware that some seeds can not be left in the water for too long or they might split in half (beans/peas type) or just get moldy right in the damp paper towel. The sowing depth should listed on the pkg. of seeds when you purchased but generally 2-3 times the width/height of the seeds/bulbs. For really tiny seeds like Lettuce, carrots etc. you can just sprinkle it on the soil and press down lightly with your hand (flat to the ground not poking down) and use spray/mist to water the seeds and they will settle in the soil by itself. Some small seeds need a light layer of soil on top and some will need light to germinate.

Google should be your new gardener friend. It will pretty much answers all of your questions, give you ideas, videos on how to do it and so much more. I got all my answers just as quick as I can type. I hope this helps and happy gardening : )