Is freezing eggs at age 33 still a good idea if considering ivf later? (at age 35-37) or would it be better just to wait?

Pros and cons: It's a good question, with no one correct answer. Oocyte vitrification (egg freezing) is nowadays very safe and effective, but the cost can be considerable. In my opinion (only) it would not be terribly cost-effective waiting between 33 to 35, but waiting until 37 or later could justify it.

Fertility decline: Fertility declines with age. IVF pregnancy rates are 10% lower in women over age 35 (compared to women younger than 35) and even lower after 38 and so on. Egg freezing allows an improved outcome at an older age since eggs were produced from younger ovaries.