When would be the best time to start my cuttings I took back before Christmas in 2015, if the weather here is suitable for gardening most of the time by mid April 2016. Right now they are in fridge with waxed ends and rolled in saran wrap. By mid April pretty much chance of all frost is gone but I will start them in pots first before planting them in the ground in my desired locations. Also  How long do I leave them in the pots if I'm lucky enough to get them to root and sprout leaves.

Now! !! Get them going indoors. Use heat mat if you have one. Not absublutly needed but makes it quicker for rooting and perfect for small cups with zip lock bags on top of them.

The temperature and container size are the biggest factors that will determine how long it will take for them to be ready. You can alter the temperature to speed them up or slow them down if you think that you might miss your mark as things progress. For instance it could take about 3-4 months for a cutting to grow roots and fill a 1 gallon container at 68f, but it might take only 2-3 months at 80f. Low humidity and short daylight hours during winter are also limiting factors to consider.

They will be ready for transplant when there are enough roots to hold the soil together without breaking apart. A good sign they are ready is roots growing out of the drain holes.

Yes, do it now!  I started cuttings back in September in Sphagnum moss.  A couple got moldy and died but I have several that are still alive.  My problem was keeping the moss moist consistently and or too much humidity.  I switched many cuttings into 1 gallon containers in mid December but now the temperature is dropping so I had to order a mat just as Figpig_66 suggested to you.  I just started working on my cuttings the last two days and I'm hoping I'll get some good results...not doing moss this time!

For me, March is a good time.  Once they're rooted, they don't have to live in the house too long and can acclimate to the outdoors sooner.  I will say that I am rooting a couple now, just to make the winter exciting.  More babying though.

I'll be starting later this month. Don't want to have to baby them for too long, and not comfortable putting them outside permanently until after april 15ish

I would think it depends on the number of cuttings and your space/free time limitations. I had some cuttings arrive with roots already starting so I stuck them in damp coir and set up lights and a heat mat. I could prob accommodate about 30 cuttings with this setup. However, I like starting in early March so that they can go directly from the rooting bin to my temporary hoop house. I had over 300 started this way last spring. I couldn't possibly fit all of those inside.

I figure about a month in the bin and 2-4 weeks in the hoop house before the plastic cover is permanently removed.

Zone 6 (central NJ)
Generally frost free by mid April but veggie planting dates are early May.

Hi tnsigger,
It all depends on what your goal is !
If you want them started asap ... well start asap.
If you want the laziest and cleanest (for the house) way, wait until march and get them rooted outside in a greenhouse as you seed your tomato plants as their heat and light needs are comparable.
If you want the laziest way of the chief of the lazy : I had to trim some trees for height control last October. I stuck the cuttings on in a bucket of water for 3 weeks and then pushed lots of them in 1 or 2 gallons ( or whatever I had on hand like a bucket where I drilled some holes at the bottom) and they are in the open in the garden... Some are in a sheltered place in my garden house. Different conditions, different testing, for fun . If I lose them, it is ok for me .
Success or not ... Lets wait for June for the result :) . But so far, I still seen green in most of the tips.
I still have some in the bucket with water. I'm planning to perhaps pot them somewhere in March if I get to it . The garden being already full of fig trees of that particular strain ...
Of course, this year is the best one for that so far, as I got sent to a virtual Zone 9 - so far. February is a cold month here, so don't sell the skin of the bear before killing it ... so they say here... - . But with 5 nights of frost ... The winter is cheap on us this year.

If those cuttings are praised ones for you ...
Well the choice is your !