Hi the first signs ive experienced is defo a change in personality like englishrose says they go moody and quiet, discharge is another sign around 3 weekish i always have mine scanned at home so its no stress at all ok it dont give you the exact amount of pups but most of the time its pretty good at confirming mum being in whelp its important if you do have her scanned not to have her done til at least 28 days or you could be told shes not when infact she is