It typically takes 4 to 6 weeks for new registration renewal tags or stickers to arrive; when renewing a vehicle's registration through the DMV by mail. There are overnight services online, such as NeedTags, which provide expedited registration renewal service and ship new registration cards and stickers same-day.
In this specific case since you've already paid your registration fees and the DMV has probably already begun processing your vehicle's registration renewal, your better option is to call the DMV at (800) 777-0133 to make sure they have received your renewal payment and allow more time for your tags arrive.
If after 6 weeks you still have not received your renewed registration, check to see that your payment was cashed and if it has, either visit the DMV to obtain a replacement sticker and card ($20 fee) or you an online service to order a replacement faster.
Note: The DMV does not take responsibility for lost mail. Once they process and send out a registration card or sticker, it becomes the United States Post Office's responsibility to deliver your renewed registration. If the DMV shows that they've mailed out your registration, and the post office never delivered it to you, you'll need to purchase a replacement.
If your tags will expire in the next 30 or so days, you may consider visiting the DMV and paying to receive a duplicate registration sticker and registration card so that you are not in violation of registration laws, and avoid the risk of getting pulled over for expired tags. You may also order replacement registration online here.
