I'm now in act 10, character level is 67. Should I be starting to worry about trying to get the stats/sockets that I need now or should I wait until I'm done with the campaign?
I have my key skills where they need to be, but still a lot of optimisation to do. Not that I'm struggling at the moment.
If you're not SSF (and you are down to trade for gear), you can start grabbing your gear at your current level. Most items will have a lower level requirement than 67. I think the highest you could reasonably expect is 69 or 70 on a budget (better bases are more expensive and have higher requirements).
If you have 15-20c, get a 6L with the colors you need (probably corrupted) or a tabula rasa if that's not available. The sockets are most important here, so it's ok to get an item with poor stats if you can't find a good one within your budget. It will be cheaper to make up for your chest with other gear than to get a good chest, at least starting out. Self crafting (buy a non-corrupted 6L base) is a good middle ground, budget-wise. Essence and good crafting are great tools for making a starter armor.
Then, (I use a spreadsheet for the following) make sure you get enough resistances to have 75 (or more, unless you want to run a curse immune flask for elemental weakness maps... Which I do) of each after the -30 penalty you'll get at the end of A10. Try to get as much resistances and life (or ES if you're not life-based) on all pieces as you can afford (at this point in the league you should be able to get really solid gear for 1-2c per piece). I usually start with the belt, helmet, and gloves, then move to rings and amulet. I save the boots for last so I can get as much movement speed as possible for my budget, but you could buy them first and make up for lacking resistances elsewhere.
Obviously if your build makes use of unique items you'll have to balance resistances on other gear. Unique chests are generally more expensive to get 6Ls than bases you'll craft yourself (not true for shaper, elder, or synth bases).