Dell 10% Email Coupon Code and Cashback?

Hi.  I am looking to order a dell xps 15 online.  I would like to get a coupon code to get discount.  I signed up for that dell email where it say they will email you a code for 10% off in the next 24 hours.  Anyone here done that and if so, how long to receive?

Also i heard of cashback sites where you get cashback if you use them to place order.  I remember back then using fatwallet and ebates and now ebates is rakuten.  I see as of now on rakuten, dell cashback is 10% as oppose to 2%.  Anyone know how often this occurs?  I want to buy a xps soon and would like to get the biggest discount since dell is already very expensive.  I also heard of other site like topcashback and that seem to offer 11% now?

Any way to know how often these 10% cashback deals happen?  That is a big discount when ordering a dell xps laptop.