如何让RadioButtonList_SelectedIndexChanged事件处理程序在asp.net C#中首次执行该事件后执行？

<asp:RadioButtonList ID="RadioButtonList1" runat="server" AutoPostBack="true" OnSelectedIndexChanged="RadioButtonList1_SelectedIndexChanged">
    <asp:ListItem Text="Option 1" Value="1"></asp:ListItem>
    <asp:ListItem Text="Option 2" Value="2"></asp:ListItem>
    <asp:ListItem Text="Option 3" Value="3"></asp:ListItem>
</asp:RadioButtonList>

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        RadioButtonList1.SelectedIndexChanged += RadioButtonList1_SelectedIndexChanged;
    }
}

protected void RadioButtonList1_SelectedIndexChanged(object sender, EventArgs e)
{
    // 事件处理程序的逻辑
}

protected override void OnInit(EventArgs e)
{
    base.OnInit(e);
    RadioButtonList1.SelectedIndexChanged += RadioButtonList1_SelectedIndexChanged;
}

protected void RadioButtonList1_SelectedIndexChanged(object sender, EventArgs e)
{
    // 事件处理程序的逻辑
}