Printing the start and end dates of the most recent eight weeks
Don't Repeat Yourself


$currentDate = date('Y-m-d');
$weekOneStart = strtotime("-56 day", strtotime($currentDate));



You can simplify this by saying something like 

$midnight = strtotime(date('Y-m-d'));
$weekOneStart = strtotime("-56 day", $midnight);


Then you don't have to keep taking strtotime of the same value.  


$weekOneEnd = strtotime("-49 day", strtotime($currentDate));
$weekOneEnd = date('m/d/Y', $weekOneEnd);
$weekTwoStart = strtotime("-49 day", strtotime($currentDate));
$weekTwoStart = date("m/d/Y", $weekTwoStart);



Similarly, consider reducing this to 

$weekOneEnd = strtotime("-49 day", $midnight);
$weekOneEnd = date('m/d/Y', $weekOneEnd);
$weekTwoStart = $weekOneEnd;


Now you only calculate that value once.  

As a for loop

$weekMarkers = [];
$midnight = strtotime(date('Y-m-d'));

for ($current = strtotime('-8 weeks', $midnight); $current &lt;= $midnight; $current = strtotime('+1 week', $current)) {
    $weekMarkers[] = date('m/d/Y', $current);
}

$previous = array_shift($weekMarkers);
foreach ($weekMarkers as $current) {
    echo "&lt;td&gt;$previous - $current&lt;/td&gt;\n";
    $previous = $current;
}


This is actually as two for loops.  You could mix them if you wanted, although many would argue that you are mixing calculation and display in that case.  

$midnight = strtotime(date('Y-m-d'));

$current = date('m/d/Y', strtotime('-8 weeks', $midnight));
for ($next = strtotime('-7 weeks', $midnight); $next &lt;= $midnight; $next = strtotime('+1 week', $next)) {
    echo "&lt;td&gt;$current - ";
    $current = date('m/d/Y', $next);
    echo "$current&lt;/td&gt;\n";
}


This would work, although the double use of $current is a bit odd.  

I leave it up to you whether either of these is easier than your original code.