how to redirect through user-home page - php

Question

I am trying to redirect the index page to user-home.php page. but when I am trying to login its showing wrong user. How to redirect to the user-home page by this condition. expecting help. Thanks in advance. The following image is the database property of the signup page.
database of signup
HERE IS MY CODE FOR INDEX PAGE
<form method="post" action="" autocomplete="on">
<h3>Log in</h3>
<hr>
<p>
<label for="username" class="uname" data-icon="u" > Your username </label>
<input id="username" name="username" required="required" type="text"/>
</p>
<p>
<label for="password" class="youpasswd" data-icon="p"> Your password </label>
<input id="password" name="password" required="required" type="password"/>
</p>
<p class="login button">
<input type="submit" name="login" value="Login" />
</p>
</form>
<h2>dont have an account signup here</h2>
<li>signup</li>
</table>
<?php
if(isset($_POST['login'])){
$username = $_POST['username'];
$password = $_POST['password'];
$q=$db->prepare("SELECT* FROM signup WHERE username='$username' && password='$password'" );
$q->execute();
$row=$q->fetch(PDO::FETCH_OBJ);
$count = $q->rowcount();
if ($count >= 1){
session_start();
$_SESSION['id'] = $row['user_id'];
header('location:user-home.php');
}else{
echo "<script>alert ('Wrong User')</script>";
}
}
?>