int width = 40, height = 40;
int count_i = 10, count_j = 10;
Bitmap bmp = new Bitmap(Convert.ToInt32((count_i * width) + (count_i * count_i - count_i)), Convert.ToInt32((count_j * height) + (count_j * count_j - count_j)),PixelFormat.Format32bppArgb);
Graphics g = Graphics.FromImage(bmp);
int input = (int)(DateTime.Parse("2017/07/06 8:00 AM") - DateTime.Now).TotalDays;
int h = 0;
for (int i = 0; i < count_i; i++)
{
for (int j = 0; j < count_j; j++)
{
    h++;
    SolidBrush b;
    if (h <= input)
    {
        b = new SolidBrush(Color.Green);
    }
    else
    {
        b = new SolidBrush(Color.LightGray);
    }
    g.FillRectangle(b, new Rectangle(i * (width + count_i), j * (height + count_j), width, height));
}
}
bitmap.Save(@"C:\Users\admin\Desktop\test.png", ImageFormat.Png);