With new skis I recommend not touching the edges at all & skiing them using the factory angles. See the base tuning section regarding the base work that is required for new skis. Only if you wish the skis to perform differently should you consider changing the factory angles. If you are happy with the factory base edge angle then all future tuning should be to the side edge angle only as additional base edge tuning will increase the base angle &/or lower the edge below the p-tex base which will then required a stone grind & a complete edge reset to correct the situation.
If you have a range of base & side edge file guides you can easily suss out the skis factory angles, assuming they haven’t been changed by a shop tune. Use a marker pen to blacken a few cm of edge & then gently use a fine stone on one of your guide to polish off the pen mark. If the stone only removes a strip of pen down the binding side of the edge then the guide being used is of a steeper angle than the actual edge. Conversely, if the stone only removes a strip of pen down the ski base side then the guide being used is of a shallower angle than the actual edge. Simply go through the guides one by one in increasing angles until the pen is equally & fully removed across the full width of the edge, & bingo, that’s the ski edge’s current angle. The same test is used for both the base & side angles.
If you don’t have a full set of guides (& most people don’t) then look up the make & model of your skis in the 'Edge Angles & Wax Data' section or email/call me with the make & model of your skis & I’ll tell you what the factory angle is.
Note that the base edge angle can only be increased, with a reduction only being possible following a stone grind of the bases. The side edge angle can be adjusted either way at any time although if you reduce the side edge angle you’re effectively removing metal off the base edge & thus shortening the life of the edge/ski.
Filing the edges removes more metal than using diamond stones so regular touching-up of the side edge angle with a diamond stone(s) removes far less metal than letting the edges get really dull & burred over & then having to file them back to the correct angles.
Note: All tuning is (usually) done on the side edge only as regular tuning of the base edge is likely to over bevel it &/or lower the base edge relevative to the ski base. However I’ve included a description of the base edge work for if/when it is needed, say following a stone grind. If you do need to work on the base edges always do that before starting on the side edges.