How long before the seedlings are ready to plant in the garden?
Unless you have very mild winters, I would wait for spring planting. Here is more information: https://www.gardeningknowhow.com/ornamental/flowers/cockscomb/growing-cockscomb-flowers.htm
https://www.gardeningknowhow.com/garden-how-to/seeds/when-to-transplant-a-seedling-plant-into-the-garden.htm
Where can I buy seeds for cockscomb flowers?
Park Seeds has a nice selection of these: http://parkseed.com/Search.aspx?ss=Cockscomb
I have plants of Harsingar (Coral Jasmine) which have not flowered for one year. When do I expect it to flower? I planted Cockscomb (Celosia) in April. There is no flowering till now. When do they flower?
For plants that aren't flowering, there are two basic causes to be considered: insufficient light, and too much nitrogen. The latter problem may be helped by working bone meal into the soil, and using less nitrogen-rich fertilizer. Here are two articles on these plants that might offer some insights: https://www.gardeningknowhow.com/ornamental/flowers/jasmine/non-flowering-jasmine.htm
https://www.gardeningknowhow.com/ornamental/flowers/cockscomb/growing-cockscomb-flowers.htm
I urge you to consult the resources available to you at the Delhi Botanical Garden to help you with any gardening problems you may have.
Neighbors have plant and I wanna start a piece if I can.
These plants don't propagate from cuttings, but you can gather seeds from your neighbor's plant, and start those. https://www.gardeningknowhow.com/ornamental/flowers/cockscomb/growing-cockscomb-flowers.htm
I have these growing in my garden but don't know what they are. Can you help?
This is a Celosia. Argenteu var plumosa
https://www.gardeningknowhow.com/ornamental/flowers/cockscomb/growing-cockscomb-flowers.htm
Will Cockscomb survive indoors during Colorado winter? I would like to bring 10 plants indoors for the winter. I know they are annuals; however, I would like to try.
Once the plants have flowered they will not produce any new plants or flowers. Celosia is an annual. You can however collect seeds for next spring.
Here is a link with more information.
https://www.gardeningknowhow.com/ornamental/flowers/cockscomb/growing-cockscomb-flowers.htm
I bought a large pot and want to grow as a houseplant.
If you have a full sun location in your home and choose smaller growing varieties you certainly can.
https://www.gardeningknowhow.com/ornamental/flowers/cockscomb/growing-cockscomb-flowers.htm