One lesson I have learnt is don't take it on an empty stomach! I settled into Tamoxifen and from today Femara early afternoon, just after lunch
Copy and paste from the Femara website
Swallow the tablet with a glass of water or other liquid.
If your stomach is upset after taking the tablet, take it with a meal or after a snack.
https://www.nps.org.au/medical-info/medicine-finder/femara-tablets
It's the thought rather than the actual that is the problem, you will settle into a routine and your body will adjust.