pls help

Nope. If they give you shit, tell them it's a known nontoxic cure( food grade). That you had to do something before they arrived. Also the d.e worked for me. Haven't seen those fuckers in years. No need for exterminators. Hopefully the exterminators don't need to come again.

Might as well vacuum, DE is ineffective against bedbugs, as are most insecticides.

Theres no trouble I can get into at all for this? Like they can't say "welp you tried to treat it yourself so you can pay the fees or ur out"?

It's effective because it gives their exoskeleton cuts and dehydrates them. It won't be a one day fix all but you will definitely see improvements after a week or two. Look if you feel that worried, vacuum it and then lay it on after they leave. Why would they get angry you tried something. It's reasonable that you tried something yourself first. Are you really going to let bugs attack you while you wait? If he gives you shit tell him to show you in the contract where it says you have to not do shit to rid your home of bugs in the simplest and earth friendly and home friendly way possible. Your attitude should be non chalant. Like, yeah I poured that on waiting for you guys to come help. I couldn't stand another itchy bite. Think if it this way. If you had rats, wouldn't it be reasonable before an exterminator came that you'd have traps?

nope diatomaceous earth is edible and not even really poison

If they try to even pull something like that take them to court. Or at least threaten them with that. What judge would side with them? The exterminator is supposed to be a final solution. If the landlord got them, that means he already signed the contract. If he never discussed it before he cant surprise you with it after. If he dies, refuse because you never agreed. Look up your contract and look up renters rights in your city and state.

https://www.thebalance.com/tenants-get-rid-of-bed-bugs-2125260
Read the first article and the third one - the one abit 6 steps tenants can take etc