It does take awhile. It should be sited in a sunny location. Try taking the liquid from a boiled dinner like corned beef and cabbage place the liquid around the base of the plant. I have had great luck getting young lilacs to flower eariler this way. Be sure you don't care about this plant coming up all over the place because the roots go from here to he__! It's almost impossible
to get rid of.
Kareen

Are you fertilizing it? Trumpet vines actually love poor unfertilized soil, so if you are, that may be the cause for excessive vegetative growth.
The second reason is lack of sunlight. They love sunlight and won't flower if they are in shade.
I have a two year old gowing in awful soil. I only add compost in the spring, but nothing else. It gets about 5-6 hours of sun. Has bloomed every year of it's short life so far.

Trumpet vines can take anywhere from 3 to 7 yrs to start flowering depending on how old the plant was when you bought it.

They can be extremely invasive.

penny

My yellow trumpet vine took 5 years to bloom after I purchased it as a small plant from Wayside. And, in a cooler summer (last year) it didn't bloom at all, since it's already in a partly shaded situation. It's blooming this year - not prolifically, but steadily. I think they prefer more sun than mine receives, and more heat than mine gets (it's shaded during the hottest part of the day).

Laurel

I have it in a sunny location that get sun about 8 or 9 hours a day. Yes I fertilize but I want it to grow I'm trying to make grow to cover the railing on my deck.

I disagree that they don't flower in shade. They may flower more prolifically in sun, but they will flower quite well in shade. I planted mine in pretty dense shade -- maybe an hour or two of sun at most in the morning and nothing else all day -- about six years ago. It's around six foot tall and gets blooms. I completely neglect it. I never fertilize it. I occasionally trim it back in spring if it looks like it's heading out into the lawn and escaping the flower bed. Other than that, no care.

I've got one that is as tall as my two story house. It gets no care at all, except that which the hummingbirds give it.
Mine gets full southern exposure.

Trimming it back mildly is like declaring war on it. It seems to double, even triple in size if you trim it a bit.