if you get the seed then folow the instructions on the packet. but if you are in the north then take the later date suggested.
if you buy them already in a pot then you can plant them where you want them to grow now. providing your soil is not frozen or covered in snow.

welcome to GoY too.

Use clean pots to avoid damping off (fungal infection that causes seedlings to collapse) and fresh potting or seed compost. Water by immersing the pots in a bowl with water up to the rim of the pots. When the water has dampened the compost lift the pots out and let them drain. Put in a propagator or inside clean clear plastic bags with the top closed. This will keep the moisture in. Keep the pots in a greenhouse or porch or on a bright windowsill. Watch out for very sunny days as even now it can be very hot through the glass and may scorch the seeds. Don't forget to label the pots! They will take varying amounts of time to germinate, possibly 2-4 or 6 weeks, so don't dispair! Once the seeds have a second set of leaves open the bag but leave the pots in, to accustom them to the air. After a week the pots can come out. Pot on into separate pots as needed and harden the plants off thoroughly before putting them outside. Good luck!