I am a working man  .I am  Very busy. .But  If I designated 3 hours a day. ,3 sittings , 1 hour each of meditation..     would it be possible to reach first jhana in a few months?  

Yes. Do 2 h samatha and 1 hour insight. Or 1/2 . 

Any advice on a good insight  technoque?

You'll find what you asked for in this thread... ¯\_(ツ)_/¯ 

Don't sell yourself short, I think you could get to second jhana very quickly, depending on how you define them.(light vs heavy)
Seems a lot hinges on your IF statement.
I recommend 2 sits of 45 minutes each per day.

Let me outline some useful hacks to the 1st and second jhana.

Satipaṭṭhāna Sutta excerpt-
...He breathes in; mindful he breathes out.“Breathing in long, he discerns, ‘I am breathing in long’; or breathing out long, he discerns, ‘I am breathing out long.’ Or breathing in short, he discerns, ‘I am breathing in short’; or breathing out short, he discerns, ‘I am breathing out short...’

Hack to first jhana-
Breath less, surf the gasp point but not so close that you gasp, just a long Breath then back to shallow. Practice long and short breaths, but mostly short. BAM! it sucks slightly but spending minutes of just very slightly suffocating sensations will create the intensity and focus that 'IS' first jhana. (In my opinion) Carbon Dioxide is a vasodilator, that means all your arteries and veins will open up and more oxygen will get to the farthest reaches of your body and mind, which I think is a useful part of meditation. This breathing just does it extremely fast.

Hack to second Jhana
you ever been on a swing set? ya? remember the feeling in your tummy as you hit the high spot? damn toot'n, breath there in the tummy and cultivate that memory of tummy pleasure, with each breath, expand that fun feeling! BAM! second jhana like cheating!

Further reading from Daniel Ingram's book-
MCTB2 - The concentration states shamatha jhanas

Good luck,
And have fun as if you were a child playing at holding your breath and laughing about this playing.
~D

Thanks dream walker.  So work on slowing breaths and concentrate in the stillness  of the pause correct?

Nope, Focus on the INTENSITY of surfing the fine edge of wanting to gasp, but not letting yourself do so, just take a longer breath or two then go back to shallow breaths. If it's not uncomfortable, you are doing it wrong, there should not be any other focus possible.
Try it ....then ask more questions.
Seriously, you might get to 2nd jhana in your first sit.
​​​​​​​~D

Oh, by the way, once you hit second jhana, THEN insite practice will be effective.
​​​​​​​~D

Ok shallow breaths almost to the point of gasp. Then deeper breaths ,then go back to shallow