Tenant will need to sign first (incl. co-signer). Deposit needs to be paid to hold the place.
Landlord does not need to wait until 8/10 (the move-in day) to sign.
In fact, if you like the renter, you want to sign it as soon as you get the signed copy + EMD back from the tenant.
Until you sign AND deliver the fully executed copy to the tenant, lease is not valid. If the tenant withdraw before you send landlord-signed copy back, the lease is cancelled. Whether you can retain deposit or not depends on what term was put on lease. (Mostly you can - check state rental act/law unless there is customized terms).
Everything can be done electronically.
