Dear Scared,
You would be surprised what can be accomplished in four hours with no interruptions. For example, she won't be dealing with ringing phones, e-mail, shouting children, or delivery people!
Suggest you outline your priorities. Personally, I hate ironing (mind you I have had helpers who couldn't iron their way out of a wet paper bag but this improves with practice!). Since you have been doing it yourself all these years, you are probably already NOT ironing underwear, t-shirts and bed linens, so remove these from the laundry hamper and put them away yourself.
If your husband needs six ironed shirts a week, then leave out six shirts to iron. A few khaki trousers or a few things of yours and that's one hour. If you want specific things ironed, make sure you leave them out and she'll make sure she leaves enough time to get them done.
Leaving three hours for cleaning. Sweeping or vacuuming the floor first, then washing floors. Presumably you're pretty tidy after all these years so scrubbing should be focussed on kitchen and bathrooms ... floors, tubs, sinks, toilets etc. That's another hour, maybe an hour 30 mins. Working from one end of the house to another will mean by the time she circles back the floors should be dry.
Another 45 minutes for a decent cleaning of kitchen, laundry area, garbage removal.
If you have children, leave the ironing at one hour max .. it's unbelievable how dirty they get even if tidied regularly
(I'm assuming your place is an average sized 2 or 3 bdrm condo as opposed to house where cleaning patios etc takes much longer). Add a good chunk of time to your 'plan' if you have any stairs.
You could make a list of things to do every week, then other things that get done less frequently. If you want the oven cleaned, spray it before you go to work. If you want the fridge cleaned, toss any offending food items before hand. Indoor windows? Takes forever .. at 4 hours a week you'll have to do it yourself.
At 4 hours, you get the basics, but no doubt she'll work efficiently and do a good job. Some weeks, chores will take longer than others. Some weeks, she won't be feeling so perky. Let her know the minimum based on what's important (like those six shirts and the toilets) and build from there.
Does that help?
She's from a trusted source so don't panic. But since she's legal she won't mind showing you her IC, which you should ask for. No point finding out that you AND your trusted source are in trouble down the road.
Good luck.