I havent yet tried to grow champaca where i live in Florida. The plant is a native of India and I can tell you about how the plant grows in native conditions.

My grandparents who live in India had a tree growing in their backyard as long as I can remember. It flowered all year round and at any given time there were tons of orange-yellow blossoms on the plant. I know my grandfather planted his tree from seed too but he planted his much before I was born so I dont know how much time it took for the first blossom etc. That tree is now about forty years old! The average daytime temperature where my grandparents live is usually 88 to 90 and average nighttime temperature from 74 to 79. Winter is a little cooler but there isnt much difference between summer and winter temperatures. I dont think the plant requires much care under those temperature conditions.

It has a very beautiful fragrance and I always thought it is one of the most fragrant flowers . You can smell it from quite far away. Its a sacred flower for Hindus in India and grown in temples a lot. Hope this helps!

Hi angelsmell-growing from seeds does take awhile for the flowering stage to be reached anywhere from 4-7 years. Grafting your seedling to an older Michelia stock will enable your young plant to flower in a year or two. Personally the flower is a bit strong for me but I have friends who like it. The plant will produce more flowers if they are picked and not allowed to set seed.

I purchased a potted one gallon michelina champaca in March. It has now grown by several feet high (what was waist high is now over my head)! I have it potted in a very large pot (so I can move it into the garage when there is a hurricane -- I've heard they don't like wind)...and, not knowing what it might like for food,I gave it a jobe fruit and nut tree spike -- which precipitated the huge growth spurt. I see no signs of it blooming though...

Hi angelsmell, did your champaca ever bloom yet? Hoping you get luckier than 6 years.

Hi, Angelsmell: I have one obtained by grafting. It blooms on my small tree more than that of alba. The fragrance is also better, especially on the balanced smooth note. But the branches are weak. Two years ago freeze killed my large plant but the small plant survived. Three of my alba trees were also fatal in my yard.
Your plant is surely different from mine on many genetic traits.
This flower here was too open, simply showing you the coloration.

Here is a link that might be useful: