The cycle does not fully display all the elements - winforms

Question

I make a grid of buttons as in the calendar, but for some reason not all of them appear
First, I loop through the array, then fill it with elements and display them, and if the loop variable reaches 7 then I lower the rendering of the buttons by 40 pixels to the bottom
It turns out like this
It should be something like this
public partial class Form1 : Form
{
Button[] January = new Button[31];
int XMounth = 400;
int YMounth = 100;
public Form1()
{
InitializeComponent();
for (int i = 1; i < January.Length; i++)
{
January[i] = new Button
{
Location = new Point(XMounth,YMounth),
Size = new Size(30, 30),
Text = Convert.ToString(i),
BackColor = Color.Orange
};
XMounth += 40;
if(i >= 7)
{
XMounth = 400;
YMounth = 140;
}
if (i >= 14)
{
XMounth = 400;
YMounth = 180;
}
if (i >= 21)
{
XMounth = 400;
YMounth = 220;
}
if (i >= 27)
{
XMounth = 400;
YMounth = 260;
}
this.Controls.Add(January[i]);
}
}
}

Answer 1

The conditions like i >= 7 are true not just once but for every number >= 7, so you reset XMounth to 400 for every number in the loop for 7 and above.
You can do this once for every specific row-break or just shorten this using modulo:
for (int i = 1; i < January.Length; i++)
{
January[i] = new Button
{
...
};
XMounth += 40;
if(i % 7 == 0) { XMounth = 400; YMounth += 40; }
this.Controls.Add(January[i]);
}