7 year old hockey stick and flex

I have a couple of new sticks for my 7 year old. He's been having a hard time raising the pick and it's been bothering him. Recently someone told me that I should be looking at sticks with 10-20 flex because they get stronger once you cut them. This is all new to me and the sticks that he has are 30 flex and will need to be cut down a decent amount. He just turned 7 and weighs around 50 lbs.

I'm considering buying him a new stick with 20 flex that I don't need to cut much. I was also thinking about leaving the length to his nose when he's on skates so that he can grow into it. The stock will be around $150.

Any help would be greatly appreciated!