Trilingual - practical tips

Just adding my experience:

My languages: Dutch, French, English, German , Thai

My girl: almost 7 (3 months to go)

To age 3 partner speaks Thai, I occasionally English, communicating 50/50 English/Thai with partner.

Age 3, daughter confiscates my iPad and evolves from children stories to Peppa Pig English 5 minutes stories.

Noticing how her English improves radically I decide to talk English with her as much as possible, say 80/20, often I just forget and talk Thai...

Age 5, accidentally finds a 5 year young friend with an iPad and they start chatting morning before school and after 5 pm, often until they get to bed...

Age 6, unfortunately Australian girl disappears to Australia, replaced by American girl, but only 1/2 weekly contacts.

She watches English Youtube children's movies at least 1h/day.

Nowadays she sometimes corrects my English...funny isn't?

Age 5, I started learning her some French. She picks up very well and has a few standard French phrases she uses almost daily.

Issue: her English reading skills are poor,  she mostly sees the letters but not the words, guessing. I need to work on this, giving reading priority as opposed to speaking French with her.

Her Thai reading is good. Since we live in Thailand Thai is 1, English is 2, French is 3.

Might add Dutch and German before she reaches 10.

I learned my second language at 10 (way too late), tri at 13, quad at 15, learned a few other languages later on working in different countries, but forgot most of it, not using is loosing it.