First week just work for biggest story so you can get fancy achievment and money to buy some stuff. And cook and try to talk with however of two you like...
With the wife get her relationship high enough(always cook from 19-21 for her and nanny, talk to her and get her stuff like dress, bikini, sexy outfit and trigger options with them(dress has some massage I think, bikini tequila shots and sexy outfit weekend to vegas option with potentially triggering very good scenes with bukkake and anal) but be carefull not to spend over 500 a week for stuff(just buy one stuff at time week after week) and maybe spend some time with gym because it adds to atractivness when you do and can trigger some option with Vegas if fitness is 50 and more). Try to trigger few scenes and be good hubby till the end with her and should get ending 5 at least.
With nanny is little trickier but talk to her, when relationship and fitness high enough take her and baby to walk in park(fitness 50 because you can trigger achievment in park if you have that much) and buy her stuff when she is willing and try to discover few achievments and to trigger few events(with her its tricky because some events require specific time). When she buys dress and ask you togo to club then you go and that will trigger endings 6,7,8,9 depending on your answers. And if you are lucky and choose nice treesome with Sandy.
Edit Oh, and when does expension coming out? This game is my favorite one due to that is realistic one then my second favorite one "Eleanor" and has really nice development of story. Hope you add lot of new content like more Nanny and Sandy stuff and more wife stuff(find it annoying that sometimes she wants something just once a week eventhough its more like real marridges that way
)