Rules around computer, mobile etc use for teens and tweens - can you share yours?

[MrsFogi]

I'm aware that if I don't have some "rules" in place now (i.e. a the tweenie stage) it will be very difficult to change things once the dcs become teens. But I'm seeing a gradual creep in time that the dcs are spending on screens and feel like I am now starting to constantly be battling to get them off the screens and having negotiations when they find reasons they "need" to be on the computer/ipad.
Can you share the rules/guidelines you have that you feel work (or indeed any you wish you had put in place before your dcs became teenagers)?

I've a 17 and a 12 yo.

I had these rules for 17yo until she had done her GCSEs.

Mobile off and downstairs at bedtime and off during h/w.
Upstairs laptop for h/w only (social media blocked)
No screens in room.

12yo currently has these restrictions

• no games on phone, actually doesn't use phone except for emergencies
• phone kept in schoolbag
• no facebook etc until older
• h/w still done downstairs

We used to have a rule no TV before lunch, but that went for DD2 when DD1 did her GCSEs as I needed to keep her quiet while I helped DD1.

We broadly have a 'rule' that DD2 has to do some form of fresh air / exercise every day during holidays or weekends. Used to have rule for DD1, but circumstances have led to that being dropped.

Much much easier to introduce rules when they are younger, and stick to them than wait until there is an issue when they are 14 and try to get a phone off them then!

DS14 and 12. Both spend a fair amount of time on screens but are both 'top set' boys in school and doing well at that. Never in trouble, homework done, work on target, they play football, cricket and do scouts. I have learned to chill a little about the whole screen thing. I remember spending hours on the ZX Spectrum back in the day and still did well at school, going on to uni, had plenty of friends etc.
The only thing I'm strict on is sleep. Phones are allowed to be charged in rooms overnight as a matter of trust, but put away half an hour before bed and if found sneaking on them will be removed overnight from then on. And we do check!