That sounds like a simple variant - I gather there are some changes in structure for the southern version which Iestyn and I need to have a chat about at some point - so I wouldn’t worry at all about when you use either of them, just go for whatever comes to mind first…
The two patterns are totally interchangeable, to the point where I only realised at about cahllenge 4 or 5 that I had gone “the other way” in this course. The only real emphasis difference between them is that you would tend to use the new pattern if you were listing thing “Mae gyda fi x, y a z”, The dal usually follows the “mae”, so “Mae dal gyda fi x”. “Mae dal x gyda fi”.
There can be a subtle emphasisi difference according to where the dal goes: Mae cath dal da fi / Mae dal da fi gath / mae dal cath gyda fi are slightly different and now I’ve written it, once you’re talking abut “y gath” “the cat”, you would use the first or second version there rather than the pattern taught in the old course - I guess that’s a foible with dal.
So main answer: there’s no difference while you’re learning. Secondary answer, once you’re comfortable and using the pattern, you’ll notice some subtle differences in real life use.
Shw mae, David? Dal is “still” as in “still doing something” or “I still have a dog”. This comes up in the first few lessons of the new course, but not until course 2 or even 3 of the old course, so if youhaven’t come acrosoo it yet, don’t worry!