A few people i've trained have found it hard to trim, one of the main reasons was they flew really ham fisted, that is clutched fist on the control which makes it really easy to overdo control movements and not be able to register that you're out of trim. I've suggested trying to just use your first 2 fingers and a thumb and it makes it a lot easier to identify when you're out of trim and sometimes helps people be a little gentler on the controls.
And as the others said don't fret too much, sometimes it depends on the instructor as well, if they're a bit more rookie they want to be 99% certain you're going to be safe whilst an older instructor with more experience will be able to tell a bit sooner when you're ready to go. Its a team effort at this point!!! enjoy it, use the dual time and ask as many questions as possible. Clearblueskyy is spot on as well, that aircraft might cost you 150-200 an hour but sitting in a chair practicing is practically free!!
And Ozgrade3, you and me must be going out with different types of womenfolk
