I am very new to the vaping scene. All the quitting thoughts and feeling that revolve around quitting cigs are still very fresh with me. The first thing I wanted to say is in regards to your post above. If your Dad looks at you with a smile that says "You're 21, what do you know?", ask him if he would be interested in reading postings from people in his age bracket. Or if he already socializes via computer introduce him here and set him up reading a thread like "Older Folks and Vaping Front Porch part 2". Who knows...the folks here are so nice that maybe he will make a few new solid friendships.
The other things I wanted to share is that even the idea of quitting smoking to some immediately raises the hairs on the back of the neck. A couple of months ago if I even talked about quitting I would get nervous to the point that I could feel my heart pounding in my ears. Be careful to go slow with your Dad. It might not happen in your three day allotment, but you may plant a seed that takes root when he is home and can think about it. Since I have always felt such anxiety when approaching the thought of quitting cigs I took an approach that gave me an out in case I failed. I told myself that I would give this e-cig thing a try and worst case scenario is I could have a cig if I wanted to. I mean I read of plenty of people that continued to smoke for a while until they adjusted to the e-cig so why couldn't I give it a try. I had nothing to lose and everything to gain. Just so you know my back story a bit. I am 50 yrs old and smoked 1 1/2 to 2 pad for about 38 yrs. Tried everything out there to quit but always felt I was giving up a part of who I was....A Smoker! My home is a multi-generational one, my husband and I live with my daughter, son-in-law, and 2 grandkids. All adults (minus me for the last 28 days yay) smoke upwards of 1 pad (outside of course). I can see them go out for smoking as well as smell them when they come in so I thought this would make it too hard for me to even think about this. As crappy of a club as it is I didn't think I could give up being part of the smokers club, but I have!! At first I cont to vape as if I was smoking. I would go outside, but instead of lighting up I would vape. This way I was still part of the club see. I know it may sound silly to some but it is what I needed to do. The fun part was a couple of days in when it was pouring rain, windy and lightning outside. I laughed and laughed at the silly one outside smoking their cigs as I sat vaping comfortable and dry. I realized I did not want to be in that club anymore. My point is to not push your Dad. You are doing a very loving thing, but he is the one that has to fight the fight and win or lose it. You cannot do it for him so please let him know you love him no matter what.
One more little point from me. I did not want a juice that tasted like cigs. I was afraid that would be too close in one way but not close enough in another way. In other words I was afraid if too close I would not lose my taste for the real thing and somewhere in my mind think they were interchangeable. I was afraid if not close enough that I would not find satisfaction and look for the "real thing". I was fortunate enough to be able to try some flavors out to see what I liked and picked something along the idea of a coffee, caramel flavor to start with. You mix your own so see if he will try some other tastes before the tobacco one. Also, even though I was a heavy long time smoker....I found that even the 18mg in vape form made me jittery, so I quickly dropped to 12 and find at night I like even 6. Make no assumptions about what may work for him, just encourage him to talk with you and other (on here maybe) before thinking it wont work.
I wish you the best of luck and remember....even if your three day plan doesn't seem like it worked, You will be planting a seed that will stay with him. Don't get discouraged if it doesn't take right away. I am still working on my family in hopes they will see the light. Just love your Dad no matter what.