First time, a suggestion please! Uncut - *So excited*

Hi,
it's my first time having a girl that is gonna explore chastity with me,
and I am so excited!

But I need a suggestion on how to wear it best.

In the past I tried a few models and all fall short, too small, or they opened up when I got hard.
Now I got one that is slightly bigger, but I am thinking what is the way to really get inside properly.

The model is a typical one:
https://www.amazon.com/gp/product/B087NX18M8/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
in the largest size.

The problem for me is mostly the diameter:
most cages get large inside, but the opening is smaller.

So, here are the suggestion I've been given, but please correct me and help me if I am missing something.
1) cold water or shower to get smaller,
2) use oil,
3) possibly use a tissue or smth around the cock to "slide inside" the cage and then remove the tissue?
I am not sure about point 3!

In the past my problem with a similar cage was that I did not get into really, and when got hard, i started to swallen in the space before the cage "tube" starts (before the penis is inside), and that led to it bending down and grow more, and basically escaping from the cage.

I have to add that I am natural, non cut, and there is quite some skin: does that make a difference?


PS:
I am sure that physically I can "gently squeeze" inside it, but I am not sure how to make it happen (the diameter is a problem if I can't get into it properly). Some times I happen to be small enough, I can see it, but even thinking about chastity makes me so big! I am not sure how to become smaller, cold water makes me medium but I am not sure it makes me as small as I can be.
I try standing upside down sometimes, but that also does not always work.

Any suggestions?

Thank you!