I started my nephew Anthony on the math program when he was ten months old, and worked with him somewhat irregularly up to about 60 dots, just showing him numbers but never got into arithmetic. Then we stopped because I stopped babysitting him in the morning. He is almost two now, his birthday is in November.
However, two days ago I was babysitting both him and his three-month-old brother, and his brother seemed bored so I decided to start teaching him numbers, as three-months old is old enough to do the regular dots (rather than the jumbo, black and white infant stimulation dots). I showed Jordan (the three-month-old) numbers one - twenty, then asked Anthony if he would like to see the dots and I gave him some problem-solving opportunities, and he remembered them all! To say the least I as very pleased, as it has been at least six months since he has seen any dots.
I would go ahead and try jumping right into equations because seeing the dots will rekindle her memory. If you show her “twenty three minus seventeen equals six” she will be reviewing the numbers twenty three, seventeen, and six without knowing that she is reviewing them. I think that just going ahead and doing the equations will probably be review enough. If you don’t think it’s necessarily “sticking” you might try doing a little bit of review, like showing her all of the numbers a few times through (in small sets of course, like showing her 0-10 one day, 11-19 the next, 20-29 the next, etc. showing each set a couple times that day in a fun and playful manner) but you probably shouldn’t go back to square one and start like it is her first time seeing dots.
For Anthony my almost two-year-old nephew, I’m just going to start addition with him and also finish teaching him numbers 60-100. I will probably do a small amount of review, like the review I mentioned above, but most of our reviewing will be seeing old numbers used in equations.