I just hatched some Serama chicks, bought them off Ebay, got 18 eggs, hatched only 7. So that's the odds you might experience. But I just incubated them like normal chicken eggs. Candled them on day 7, 14, 17, I put them in lockdown on day 17. and all 7 hatched on day 20.
If that helps.
Setramas are a joy as chicks but, they don't always make it to adulthood: 'Also Seramas can carry a lethal gene in them called the 'diluted gene', which comes from the Japanese bantam, this means that chicks, could die 24 hours after hatching, or die prematurely (not for the light hearted).'
Yes seramas can be very hard to hatch I bought 3 chicks from a breeder 6 months on they all great and such a friendly breed he is a pic of my cockerel Russel Crowe if you do hatch any make sure u show us some pictures