For me it took me a good while. I learned from her dad. I started off just boarding on timber frame buildings, lovely 15mm soundboards, done that for about 18 months to enable me to get to a level where i was earning enough money to get some saved before going to basically a labourers wage whilst learning how to skim again on new builds. Learned how to mix, tape, bead, clean etc then then when had enough time on me hands was allowed to stand by spot board and practice getting it off handboard to trowel, then small cupboard walls and then built up from there. Stayed on just skimming for about 2 and a half years. From that then went on to learn all aspects of metal ceilings and studs as well as the metsec. Stayed on that for about 18 months and earned some really good money. Then went and learned how to float and skim, render and screed whilst doing a mixture of the others after that whilst doing extensions and stuff like that. So in answer it took me about 7-8 years as i spent a good while on each aspect along the way whilst i got some money in to cover me lifestyle!