I need help with a project in C #

Good, I'm doing a project in windows form and what it does is upload an excel file pass the data to a dataGridView and save them in a MySQL database, the problem is that this excel shows data of a cycle of 4 months and this is the last month therefore shows FEBRUARY, MARCH, APRIL AND MAY next month will show JUNE, JULY, AUGUST AND SEPTEMBER I do not know how to change the name of the months as it corresponds to each period, I thought about creating the base of data with 12 months and go filling according to the header of the dataGridView but I do not know how I can save it in a variable or something.

I leave the code so you can help me.

THIS IS THE IMPORTAEXCEL CLASS

class importarExcel
{
    OleDbConnection conn;
    OleDbDataAdapter MyDataAdapter;
    DataTable dt;

    public void importarExcel(DataGridView dgv, String nombreHoja, string ruta)
    {
        try
        {

            conn = new OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;data source=" + ruta + ";Extended Properties='Excel 12.0 Xml;HDR=Yes'");
            MyDataAdapter = new OleDbDataAdapter("Select * from [" + nombreHoja + "$]", conn);
            dt = new DataTable();
            MyDataAdapter.Fill(dt);
            dgv.DataSource = dt;

        }
        catch (Exception ex)
        {
            MessageBox.Show("La ruta y/o el Nombre de la hoja son incorrectos");
        }
    }

THIS IS THE BUTTON CODE TO FIND THE FILE

        string ruta = "";

        OpenFileDialog openfile1 = new OpenFileDialog();
        openfile1.Filter = "Excel Files |*.xlsx";
        openfile1.Title = "Seleccione el archivo de Excel";
        if (openfile1.ShowDialog() == System.Windows.Forms.DialogResult.OK)
        {
            if (openfile1.FileName.Equals("") == false)
            {
                ruta = openfile1.FileName;
                textBox1.Text = ruta;
                textBox2.Text = "";
                textBox2.Focus();
                textBox1.Enabled = false;
            }
        }

THIS BUTTON CODE TO IMPORT DATA TO DATAGRIDVIEW

string nom = textBox2.Text;
string ruta = textBox1.Text;
new importar().importarExcel(dataGridView1, nom, ruta);

AND THIS BUTTON CODE TO RAISE TO THE BD

        foreach (DataGridViewRow row in dataGridView1.Rows)//CICLO PARA RECORRER LA TABLA
        {
            a1 = Convert.ToString(row.Cells["Sold-to party"].Value);
            a2 = Convert.ToString(row.Cells["Ship-to-party"].Value);
            a3 = Convert.ToString(row.Cells["Cliente"].Value);
            a4 = Convert.ToString(row.Cells["Cotización"].Value);
            a5 = Convert.ToString(row.Cells["Material"].Value);
            a6 = Convert.ToString(row.Cells["Descripción"].Value);
            a7 = Convert.ToString(row.Cells["Febrero"].Value);
            a8 = Convert.ToString(row.Cells["Marzo"].Value);
            a9 = Convert.ToString(row.Cells["Abril"].Value);
            a10 = Convert.ToString(row.Cells["Mayo"].Value);
            a11 = Convert.ToString(row.Cells["Total Cotizado"].Value);
            a12 = Convert.ToString(row.Cells["PO Number"].Value);
            a13 = Convert.ToString(row.Cells["Cantidad Cotización"].Value);
            a14 = Convert.ToString(row.Cells["Cantidad OC"].Value);
            a15 = Convert.ToString(row.Cells["Valor OC"].Value);
            a16 = Convert.ToString(row.Cells["Éxito"].Value);
            a17 = Convert.ToString(row.Cells["SBU"].Value);

            string estado="";//VARIBLE HAY QUE PROGRAMAR EL ESTADO

            con.ingresarcotizaciones(a1, a2, a3, a4, a5, a6, int.Parse(a7), int.Parse(a8), int.Parse(a9), int.Parse(a10), int.Parse(a11), a12, int.Parse(a13), int.Parse(a14), int.Parse(a15), int.Parse(a16), int.Parse(a17), estado);

I hope you can help me.