Fix it now or wait?

[rich006]

It's a daily driver and I don't mind a little rust, but I want to keep as much original metal as I can, and it's visibly spreading pretty fast. If I let this go for a while, will it be harder to fix (or more expensive) later? Or am I in for the same kind of repair whether I do it now or later?
Passenger side (the white stuff is old wax):

and driver's side:

 

[ScampMike]

nip it NOW if you can - allowed to grow, it will cost you more to have it done later... you're probably in for a surprise as that kind of thing is typically worse where you can't see it

 

[bbrroowwnn]

that passenger side looks like it has bondo in it already so I think it was fixed before.....As stated when you get in there it is probably going to be worse than you think

 

[Sedanman]

Your just seeing the visable issue and it's more than likely worse when you dig into it.

 

[clinteg]

Inner quarters are probably suspect too. As long as you keep the car dry, the rust won't grow too much. But if you're going to be constantly driving it rain or shine, then that will get worse in a hurry.

 

[RustyRatRod]

Fix it now, or regret it later.

 

[RedFish]

The only difference between today and tomorrow is how much of that quarter will be replaced.
If I needed to wait for the time and money to fix and paint the whole car I would first remove the plugs in the turn downs underneath and flush that area well from inside the trunk, then flood treat it with a rust reformer product. I've used the water based Rust Ender with satisfactory results.
That along with a new trunk lid seal didn't cure the cancer but did slow it waaaaay down.

 

[rich006]

If I needed to wait for the time and money to fix and paint the whole car I would first remove the plugs in the turn downs underneath and flush that area well from inside the trunk, then flood treat it with a rust reformer product. I've used the water based Rust Ender with satisfactory results.

Now that I've started cutting into it I understand what you mean by turn downs. Rust Repair Maiden Voyage