Distributed expansion gaps in solid hardwood flooring
Do NOT install expansion spaces between each board. You want a very tight fit between each board and then leave an expansion space around the perimeter of each room. 

First you’ll need to acclimate the wood to your house. This may vary by location and season, but generally the manufacturers recommend about 10 days. 

Second, seal the floor (again, according to the manufacturer’s recommendation). 

Third, lay the “sleepers” out according to the size of your flooring and the allowable span. Sleepers are NOT fastened to the floor. They are designed to “float” or slide depending on expansion of the flooring. 

Next lay out the flooring (loosely). This will give you an idea of color, etc., but will also help acclimate the finish flooring. Gaps at the perimeter is based on the size of the room. When we do gymnasiums, we leave a 2” gap and cover with an appropriate base. In homes, we generally leave a 1” gap. 

See MFMA recommendations for acclimation and installation:  https://www.maplefloor.org/ForArchitects/Installation.aspx

Btw, to test your finish flooring, hold a piece vertically and insert another piece into the T&amp;G edge. If it fits tight, it’s okay. If not, you’ll have problems with the T&amp;G edges when you walk on them. They’ll snap and pop and drive you nuts. If it’s not tight (and supports the other piece of wood when held vertically,) then I’d send it back. (See MFMA guidelines.) https://www.maplefloor.org/Home.aspx

Btw, yes, I know it’s the Maple FlooringManufacturing Association, but is consistent with ash, etc. too.