Firewall and Iptables: setup for parental control

Hi friends,

I've recently installed OpenWrt 18.06 in an old "Wifi Extender" (TL-WA860RE v1). I set it up as a Wifi AP, and configure some Firewall rules.
I plan to use it for parental control: only the tablet of my son is going to connect to internet through the OpenWrt router.

I use another machine as a proxy with Squid, filtering ads and inapropiate content. I also use OpenDNS.

I set several rules in the OpenWrt FW to limit internet access hours, in this way:
- Within the timeframe all internet will be accesible: apps like youtube, telegram, spotify, etc. and websurfing.
- Out of the "allowed" timeframe only some websites are allowed, and the rest (apps, other websites, etc.) will be forbbiden.

The point is I'm not able to set the exception to allow visit only certain websites out of the "internet timeframe". During this timeframe all internet access is blocked, doesn't matter whatever I try...

I've tried parsing next lines in the "Custom Section" of fw config, but it doesn't work.

iptables -A OUTPUT -p tcp -d -j ACCEPT
iptables -A OUTPUT -p tcp -d -j ACCEPT
iptables -A INPUT -p tcp -d -j ACCEPT
iptables -A INPUT -p tcp -d -j ACCEPT

I've tried some setup using the console, however my linux/networking knowledge is very low...

Please could you help me with this setup?

Thanks for your time!

The rules won't work, you are applying them to a wrong chain.
Better read the documentation of what you could do.