Hello, welcome to Garden Web! Sorry no one has come in to help you, I will have a go! (I live in the UK and think I am zone 8).
I started mine on 16th Jan and I too found that it was several weeks before any leaves showed. On saying that, I've had a look at your mango pic and to me it seems as though it may be short of light as the stem looks exceptionally long and thin. Once the sprout showed above the seed I gave mine full light. The leaves are really tiny, thin and delicate to start with and reddish in colour. It seems from what I have read that mangoes grow some stem, then a set of leaves, then some more stem and so on. Here's a pic of mine taken on 28 Feb, with another seed ready to plant....

This pic was taken on 26th March

Today, one month on from last pic, it looks exactly the same apart from a tuft of 6 or so new leaves that's just showing, so, they certainly take their time.
I scrubbed the flesh off the seed case, prised the case open carefully with a sharp knife and took out the large bean shaped seed. This was then put between 2 sheets of very wet kitchen paper on a sealed plastic tub and put in the warmth of the hot water cylinder cupboard till it sprouted a root, it was VERY quick to do this, only 4-5 days. You have to check daily to make sure its still moist and see if it has sprouted. I then put it into a 3inch pot with part of the seed showing. Within a day or so the stem appeared and I grew it on...pic 1. It's now in the next size pot up from the original one...pic 2. Not sure if your seedlings will deveop into strong enough plants, as they look a bit weak and spindly, but if you decide to enjoy another delicious mango or two, or three, do have another go and try this...
Another tip may be to use a smaller pot and fill it up a little more so the seedling is not searching for the light and put it in a sunny spot.
I hope this will help you...if I can help again, let me know!
Oh, mine is my favourite 'Kent' mango btw, a lovely juicy and smooth variety we get over here, not that I ever expect mine to fruit...in the UK, you must be joking, but it's fun to try and grow one.
God luck....Gill.

I've had some problems with mango seedlings as well. i had one that got very tall but the leaves kept falling (ended up being root rot). Once i found the problem i eased off on the watering and cut the stem considerably and that's when it started getting better and branched out. if you decide to chop part of the mango stem off the new leaves (branches) will start looking like small spikes coming off of the stem near the top.

regards,

-ivan

Thank you all so much for the interest taken..i think i will put in a sunnier place..although right now it enjoys the sunniest place indoors..south facing window..nevertheless ,i shall keep it outside tomorrow and see for a week..i have 2 more in smaller pots and they too seem to be growing similarly..well more mangoes to be eaten i guess..(not that i am complaining..! i love mangoes!)

Sanketi, mangos do require a load of sunlight..even a south window won't emit light as it would outside..plus, open, fresh air will benefit. Good luck..Toni