First up is if you are trying to install from Apples Recovery Servers you really need to have your Mac connected to your router using a cabled connection, WiFi is too unreliable, and has the habit of resetting the date back to today.
As you have a MacBook you will need to use either a Thunderbolt to Ethernet cable or a USB to Ethernet cable.
If you can do that you may want to try resetting the date back again and trying to download.
If you want to try again read this.
Boot to your Recovery HD, click on Utilities in the menubar select Terminal.
Make sure WiFi is switched off, it can reset the date back to today.
Enter a new date, for example or just copy and paste
sudo date -u 011421002016
press Return
enter your password
press Return
If Terminal returns an error saying sudo : command not found, then try again without sudo.
Now try downloading the OS.
If this works then when the OS is installed and booted up you can Open System Preferences> Date & Time
and reset the time back to today.
OR:
If you have or can borrow another mac that you know can run or has run El Capitan at one time you
can try the following method.
How to upgrade to OS X El Capitan – Apple Support
Go to Section 4 and click on Download OS X El Capitan.
This downloads InstallMacOSX.dmg to your Downloads folder.
When downloaded open to InstallMacOSX.pkg, double-click on
that and an installation window will open, this does not install El Capitan
but converts the .pkg to the Install OS X El Capitan.app which you will find in
your Applications folder, it should be 6.2GBs in size.
Now that you have the Install OS X El Capitan.app in the Applications folder you can create a
bootable USB installer using the createinstallmedia command in the Terminal app.
Read the instructions here,
How to create a bootable installer for macOS – Apple Support
Having created the bootable USB installer plug it in to your mac.
Restart the mac whilst pressing and holding down the option/ alt key,
in a minute or two you should see the Startup Manager, this shows the bootable
volumes attached to your mac, select the USB installer and press Return.
The mac will now boot to the USB installer, when booted up you will see a Utilities panel
select Install OS X and click Continue. The installer screens should open, follow the prompts
at some point you will be asked to choose which disk you want to install El Capitan on
make sure you choose your macs internal disk, probably called Macintosh HD.