When expanding try and plan so when you are ready to start on your training ground and medical that you start those when you receive your two rest packs and treatments - you receive these every four days. Starting building of these two whilst it is generating health packs and you won't receive them.
Same goes for expanding your Training Ground - although this may not be as important to you. Two new youth players are generated every 28 days (IIRC on lowest level) and starting building on Training Ground will interrupt youth development.