Force Visible Property to Apply During Button Click - asp.net

Question

I'm trying to hide a button and replace it with a label until a query finishes to populate a grid view. My button .aspx page looks like so:
<asp:Panel runat="server" ID="pnlSelect" HorizontalAlign="Center" >
<asp:Label runat="server" Text="Please Select an Item" />
<br />
<br />
<asp:DropDownList runat="server" ID="ddlItems" AutoPostBack="true" />
<br />
<br />
<asp:Button runat="server" ID="btnItemSubmit" Text="Submit" /> <asp:Label runat="server" ID="lblItemSubmit" Text="Please Wait" Visible="false" />
</asp:Panel>
and here is the .aspx.vb code behind that is handling execution:
Protected Sub btnItemSubmit_Click(sender As Object, e As EventArgs) Handles btnItemSubmit.Click
btnItemSubmit.Visible = False
lblItemSubmit.Visible = True
oracleSql()
btnItemSubmit.Visible = True
lblItemSubmit.Visible = False
End Sub
My problem is that the properties don't apply until after the sub finishes execution, at which point no changes are visibly made because the properties immediately went back to how they were originally. Is there a way to get these properties to apply asynchronously?
Edit:
Here is Page_Load
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Page.IsPostBack Then
'was causing query to reload on button click and default back to first item on list, this way allows it to retain whichever item was selected
'setting postback = false on ddl did not resolve the issue either
Else
Dim oracleConn As New Oracle.DataAccess.Client.OracleConnection
oracleConn.ConnectionString = ConfigurationManager.ConnectionStrings("ConnString").ConnectionString
Dim sql As New Oracle.DataAccess.Client.OracleCommand
sql.CommandType = CommandType.Text
sql.CommandText = "select * from Items order by 1"
sql.Connection = oracleConn
Dim dataAdapter As New Oracle.DataAccess.Client.DataAdapter(sql)
Dim dataSet As New DataSet
dataAdapter.Fill(dataSet)
ddlItems.DataSource = dataSet
ddlItems.DataTextField = "item_name"
ddlItems.DataValueField = "item_id"
ddlItems.DataBind()
End If
End Sub
oracleSql() is similar to this, just binding to a gridview instead of a ddl.

Answer 1

Based on recommendations from JohnPete22, I ended up creating a simple Javascript function to handle this:
<script type="text/javascript">
function hideShowBtn() { document.getElementById('btnItemSubmit').style.visibility = 'hidden'; };
</script>
I then added it to the OnClientClick property of my button:
<asp:Button runat="server" ID="btnItemSubmit" Text="Submit" OnClientClick="hideShowBtn()" />
The button would disappear when clicked and return after PostBack.