Starting funds vary depending on how many Sims and how old those Sims are, however, For one Sim it's §16,500, +§2,000 per additional adult, +§1,500 per teen, +§1,000 per child, +§500 per toddler. So a family consisting of parents with a teen would start off with §16,500 + §2,000 + §1,500 = §20,000. That is the rule of thumb (as they say).
Merry Christmas Simmers and I wish you all a prosperous and happy New Year
KJ