Just over 4 years between eldest and DTwins. longer than we were aiming for, but all worked out for the best especially as there were 2 babies! Really really useful that eldest was fully potty trained, could dress herself, amuse herself for relatively extended period when needed.
Next one is due when DTwins will have just turned 3. Bit nervous about that if I'm honest, potty training is not going well and they still fight over my lap/cuddles! We assumed it would take a while to conceive again but it didn't....