javascript - D3 ticks every 4 months but starting in first domain date -

i wan create line chart in d3,but want show ticks every 4 months because need show ticks every point have data in chart.

i used this:

// xscale time scale obj d3.time.scale()  xaxis = d3.svg.axis()   .scale(xscale)   .ticks(d3.time.months, 4)   .orient('bottom'); 

ant works, ticks show 2 days after initial date in data:

it show @ 1/january/2015 when first data in 30/december/2014

how can set initial tick in specific point , set 4 months interval?

i believe d3 time scale try space dates evenly (and i'm not sure there way specify specific dates). if know dates want displayed, can use ordinal scale dates inputs.