Experts and BHG readers answer.
Please excuse our delay in responding to your question; our Web site was down unexpectedly for a few weeks. You can kill the existing grass now with a non-selective herbicide, then dig it up. Make sure it is completely dead and gone, along with any weeds and debris, before you re-sod. Then prepare the soil by working in good quality topsoil. The best time to put down sod is early autumn or spring.