Start now. Get a glass of water into you. Taste? Maybe start with lemon (real) squeezed in. But – you will need to source good water. It is more important than the food you choose.
Find yourself a decent water filter. It MUST take out all fluoride and chloride, and give you SOFT water – see more on magnesium and its importance here Minerals and pH are desperately important. This is seriously needed as the flushing of life residue in these modern times is one of the most important health considerations you can muster. In the meantime – find a source of soft (pH 8 is great) water to start guzzling – at least a litre – in small amounts in the morning and ease into at least 1.5 litres- before you look at any food or other beverages. This is THE most single useful health tip. Pure, not cold, or even cool water though. Municipal tap water is likely adulterated and needs fluoride and chloride filtering.
Please download these pdfs – brilliant articles as to WHY water matters